v. Shanks , 2019 COA 160 ( 2019 )


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  •      The summaries of the Colorado Court of Appeals published opinions
    constitute no part of the opinion of the division but have been prepared by
    the division for the convenience of the reader. The summaries may not be
    cited or relied upon as they are not the official language of the division.
    Any discrepancy between the language in the summary and in the opinion
    should be resolved in favor of the language in the opinion.
    SUMMARY
    October 24, 2019
    2019COA160
    No. 17CA0495, People v. Shanks — Evidence — Opinions and
    Expert Testimony — Testimony by Experts
    In this criminal appeal, a division of the court of appeals
    considers whether a trial court must conduct a Shreck hearing
    before admitting expert witness testimony analyzing historical cell
    site data. As an issue of first impression, but consistent with most
    federal courts, the division holds that the use of historical cell site
    data to determine the general geographic location of a cell phone is
    widely accepted as reliable and does not require a Shreck hearing.
    In so holding, the division distinguishes historical cell site analysis
    from the theory of granulization, which remains a source of
    controversy within the scientific and forensic communities.
    Because the evidence offered at trial was within the bounds of
    reliable historical cell site data analysis, it was properly admitted.
    The division also rejects the defendant’s contentions that the
    district court erred in denying his motion to suppress the victim’s
    out-of-court identification and in admitting the victim’s in-court
    identification; that the district court violated his rights to due
    process, to present a defense, and to a fair trial by disallowing
    certain evidence in support of and not instructing the jury on an
    alternate suspect defense; and that the district court erred by
    allowing reference to his nickname during trial.
    Accordingly, the division affirms the judgment of conviction.
    COLORADO COURT OF APPEALS                                          2019COA160
    Court of Appeals No. 17CA0495
    Jefferson County District Court No. 14CR2888
    Honorable Tamara S. Russell, Judge
    The People of the State of Colorado,
    Plaintiff-Appellee,
    v.
    Charles Jenson Shanks,
    Defendant-Appellant.
    JUDGMENT AFFIRMED
    Division III
    Opinion by JUDGE BROWN
    Furman and Davidson*, JJ., concur
    Announced October 24, 2019
    Philip J. Weiser, Attorney General, Jillian J. Price, Senior Assistant Attorney
    General, Denver, Colorado, for Plaintiff-Appellee
    Lauretta A. Martin Neff, Alternate Defense Counsel, Grand Junction, Colorado,
    for Defendant-Appellant
    *Sitting by assignment of the Chief Justice under provisions of Colo. Const. art.
    VI, § 5(3), and § 24-51-1105, C.R.S. 2019.
    ¶1    Defendant Charles Jenson Shanks appeals from his conviction
    on two counts of kidnapping, two counts of burglary, and one count
    each of robbery, felony menacing, assault, and false imprisonment.
    He contends that the district court erred by (1) admitting expert
    witness testimony about historical cell site analysis without first
    conducting an evidentiary hearing; (2) admitting an impermissibly
    suggestive out-of-court identification and an in-court identification
    based thereon; (3) excluding his alternate suspect defense; and (4)
    allowing the use of his nickname, “Capone,” at trial. He also
    contends that the cumulative effect of these errors warrants
    reversal. We affirm.
    ¶2    Addressing an issue of first impression in Colorado, we
    conclude that expert testimony explaining how historic cell site data
    is used to provide a general geographic location of a cell phone at a
    given time may be admitted without first holding an evidentiary
    hearing on the reliability of the methodology.
    I.   Background
    ¶3    Shanks and his codefendant, William Cody, were charged with
    numerous offenses arising from the home invasion and assault of
    the victim.
    1
    ¶4    The victim and Cody worked together and occasionally
    socialized outside of work. The victim supplied Cody with
    marijuana and the two men sometimes smoked marijuana together.
    On the night of the charged offenses, Cody called the victim to
    purchase some marijuana and arranged for his “sister,”
    codefendant Arianna Eastman, to pick it up for him.
    ¶5    The victim met Eastman outside his house for the transaction.
    When he turned to go back inside, a masked man, whom the victim
    later identified as Cody, and another unmasked man followed him
    and forced their way inside. The two assailants searched the
    apartment and beat up the victim before leaving with the victim’s
    equipment for growing marijuana.
    ¶6    A couple of days after this incident, the victim identified
    Shanks as the second assailant from a photo array. The victim
    identified Shanks again during trial.
    ¶7    A jury ultimately convicted Shanks as charged. The court
    sentenced him to twenty-eight years in the custody of the
    Department of Corrections.
    2
    II.    Historical Cell Site Analysis
    ¶8     Shanks contends that the district court erred by admitting
    expert witness testimony analyzing historical cell site data without
    first holding a hearing to determine the reliability of the science
    behind such analysis. We disagree.
    A.        Standard of Review
    ¶9     We review the district court’s admission of expert testimony for
    an abuse of discretion and will reverse only when the decision is
    manifestly erroneous. See People v. Rector, 
    248 P.3d 1196
    , 1200
    (Colo. 2011). “This deference reflects the superior opportunity of
    the trial judge to assess the competence of the expert and to assess
    whether the expert’s opinion will be helpful to the jury.” 
    Id.
    B.    Applicable Law
    ¶ 10   A trial court determines the admissibility of expert testimony
    under CRE 702, which provides as follows:
    If scientific, technical, or other specialized
    knowledge will assist the trier of fact to
    understand the evidence or to determine a fact
    in issue, a witness qualified as an expert by
    knowledge, skill, experience, training, or
    education, may testify thereto in the form of an
    opinion or otherwise.
    3
    The inquiry focuses on “the reliability and relevance of the proffered
    evidence and requires a determination as to (1) the reliability of the
    scientific principles, (2) the qualifications of the witness, and (3) the
    usefulness of the testimony to the jury.” People v. Shreck, 
    22 P.3d 68
    , 70 (Colo. 2001); accord People v. Campbell, 
    2018 COA 5
    , ¶ 40.
    The court must also evaluate the evidence under CRE 403,
    ensuring that the probative value is not substantially outweighed by
    the danger of unfair prejudice. See Rector, 248 P.3d at 1200;
    Shreck, 22 P.3d at 70.
    ¶ 11   The court’s inquiry “should be broad in nature and consider
    the totality of the circumstances of each specific case.” Shreck, 22
    P.3d at 77; accord Rector, 248 P.3d at 1200. Although the factors
    set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc., 
    509 U.S. 579
     (1993), provide helpful guidance, a court need not consider any
    specific set of factors when determining the reliability of the
    proffered evidence. Shreck, 22 P.3d at 78.
    ¶ 12   Concerns about conflicting opinions or whether a qualified
    expert accurately applied a reliable methodology go to the weight of
    the evidence, not its admissibility. See Campbell, ¶ 42. “Such
    concerns ‘are adequately addressed by vigorous cross-examination,
    4
    presentation of contrary evidence, and careful instruction on the
    burden of proof.’” Id. (quoting Estate of Ford v. Eicher, 
    250 P.3d 262
    , 269 (Colo. 2011)).
    ¶ 13   If a party requests that evidence be subjected to a Shreck
    analysis, the trial court may, in its discretion, hold an evidentiary
    hearing. Id. at ¶ 41. “This discretion comports with the trial court’s
    need to ‘avoid unnecessary reliability proceedings in ordinary cases
    where the reliability of an expert’s methods is properly taken for
    granted, and to require appropriate proceedings in the less usual or
    more complex cases where cause for questioning the expert’s
    reliability arises.’” Rector, 248 P.3d at 1201 (quoting Kumho Tire
    Co. v. Carmichael, 
    526 U.S. 137
    , 152 (1999)). A hearing is not
    required if the court “has before it sufficient information to make
    specific findings under CRE 403 and CRE 702 about the reliability
    of the scientific principles involved, the expert’s qualification to
    testify to such matters, the helpfulness to the jury, and potential
    prejudice.” 
    Id.
    C.    Additional Background
    ¶ 14   Shanks’s defense was that he was not the second assailant
    and that he was at a family gathering on the other side of town
    5
    (about eighteen miles southeast of the victim’s house) at the time of
    the offense. The prosecution intended to disprove this defense by
    introducing evidence from Shanks’s phone records and cell tower
    usage data to show that he was in the general area of the victim’s
    home at the time of the offense. To do so, the prosecution disclosed
    investigator Kathleen Battan as an expert in “Forensic Analysis of
    Cellular Phone Records and Cell Tower Function and Data.”
    Defense counsel objected and requested a Shreck hearing.
    ¶ 15   In its order denying the hearing request, the district court
    noted that whether a Shreck hearing is required to determine the
    admissibility of historical cell site analysis is a novel issue in
    Colorado. It then reviewed federal case law analyzing the issue
    under Fed. R. Evid. 702, which is similar to Colorado’s rule for our
    purposes, before ruling that
    federal courts have generally required a
    pretrial hearing to determine the admissibility
    of expert testimony purporting to pinpoint the
    location of a defendant using cell phone site
    data, whereas a pretrial hearing has generally
    not been required to determine the
    admissibility of testimony merely purporting to
    place a defendant within the service radius of a
    specific tower at a certain time.
    6
    Concluding that the prosecution’s proffered evidence fell into the
    latter category — identifying Shanks’s general location when the
    crime was committed — the district court denied the request for a
    hearing.
    ¶ 16   Shanks renewed his objection and request for hearing multiple
    times, arguing that Ms. Battan based her opinion on a theory called
    “granulization” and the “scientifically unsupported assumption that
    a cell phone connects to the closest cell tower.” Shanks also
    challenged Ms. Battan’s use of pie shaped sectors rather than ovals
    to demonstrate the cell tower service area. Again, the district court
    denied the request for hearing.
    ¶ 17   At trial, over Shanks’s objection 1, the district court accepted
    Ms. Battan as an expert and allowed her to testify “about forensic
    analysis of cellphone records . . . and also in a limited fashion about
    . . . cell tower function and data.” The court acknowledged that Ms.
    Battan did not have a background in science or engineering but
    1 Shanks did not object to Ms. Battan’s analysis of cell phone
    records or her mapping or identification of the cell towers used to
    make particular calls. Instead, Shanks objected to Ms. Battan’s
    “analysis of sectors, what sectors mean and general technical
    operations of a cellphone tower.”
    7
    concluded she did not need to “know how to design, operate or
    manufacture cell towers” to testify about the cell tower data she
    collects and “what that data tells her about cell tower function.”
    ¶ 18   Ms. Battan testified to the following:
    • Typically, a cell tower has three sectors, each covering
    approximately 120 degrees of a 360-degree circle around
    the tower. The orientation of the sector (the precise
    direction the sector points) is called the azimuth.
    • Law enforcement has access to a database that includes
    the precise physical location of all cell towers and the
    azimuth of each sector of each tower.
    • Shanks’s cell phone carrier produced records that
    included data about when each call was made or
    received, how long the call lasted, and what specific
    sector of what cell tower was used by the cell phone to
    make or receive the call.
    • She mapped the physical location of the cell towers used
    by Shanks’s carrier using Google Earth; identified the
    towers closest to Shanks’s residence, Cody’s residence,
    8
    and the victim’s residence; and noted that there were
    approximately 100 towers in between.
    • Using an FBI computer program, she plotted the cell
    tower and sector used for each relevant call reflected in
    Shanks’s phone records. The sectors associated with
    each call were reflected on the exhibits as 120-degree
    wedges with green lines as the general boundaries of the
    sector and a shaded green area between the lines. The
    lines did not depict distance from the cell tower.
    2
    2For reader clarity, we have included a map that was part of a trial
    exhibit reflecting how Battan mapped the sectors.
    9
    • She cannot state how far away a cell phone is from a
    given cell tower during a call or exactly where a cell
    phone is when it uses a particular tower.
    • Many cell tower coverages overlap and a call typically will
    use the cell tower with the clearest and strongest signal
    even if that tower is not the closest. Which tower a
    phone uses is determined by the carrier based on a
    variety of factors.
    ¶ 19   With this background, Ms. Battan testified about and
    presented exhibits showing the cell towers and sectors used by
    Shanks’s cell phone to make and receive calls before and after the
    attack on the victim. Between 10:36 a.m. and 4:00 p.m., Shanks’s
    phone connected with towers near his home in Aurora. Between
    4:55 p.m. and 7:39 p.m., Shanks’s phone connected with towers
    moving west along the highways between his home and Cody’s
    home in Lakewood. Between 9:00 p.m. and 10:08 p.m., Shanks’s
    phone made or received six calls by connecting to a west-facing
    sector of a tower situated southeast of the victim’s home in
    Edgewater. At 10:27 p.m. the victim called 911 to report the attack.
    10
    At 10:39 p.m., Shanks’s phone again connected with the tower
    nearest Cody’s home.
    ¶ 20   Ms. Battan performed a similar analysis of cell phone records
    for Cody and Eastman. Collectively, the data revealed several
    communications among Shanks, Cody, Eastman, and the victim
    from 9:04 p.m. to 9:51 p.m., and further communications between
    Shanks’s phone and Eastman’s phone between 10:02 p.m. and
    10:08 p.m. Shanks’s, Cody’s, and Eastman’s phones connected to
    towers near the victim’s home for these communications.
    ¶ 21   Notably, Ms. Battan did not opine that Shanks or his phone
    was in any specific location at any specific time. Nor did she testify
    regarding the overlap in coverage between two cell towers or to the
    range of any tower with which Shanks’s phone connected the night
    of the incident. She also did not testify to the typical coverage
    range of a tower, instead explaining generally that the range of a
    tower in an urban area like Denver will be much shorter than in a
    rural area like the middle of Kansas because of the concentration
    and availability of towers, heavy usage, and physical interference in
    urban areas. Ms. Battan did say, on cross-examination, that she
    believed it was impossible for Shanks’s phone to be eighteen miles
    11
    to the southeast of the tower nearest the victim’s home at the time
    it connected to the west-facing sector of that tower.
    ¶ 22   To counteract Ms. Battan’s testimony, Shanks offered a
    competing expert, Joseph Kennedy. Over the prosecution’s
    objection, the district court accepted Mr. Kennedy as an expert in
    “radio frequency, which includes cell phone tower operations and
    cell phones.” Mr. Kennedy testified to the following:
    • Many cell tower coverages overlap and a call typically will
    use the cell tower with the best call quality, even if that
    tower is not the closest. Which tower a phone uses is
    determined by the carrier based on a variety of factors.
    • Typically, a cell tower has three sectors pointing in three
    different directions. No sector is precisely 120 degrees.
    • One cannot say a cell phone is near a tower simply
    because it connects to that tower. A cell phone can be
    serviced by and connect with any tower within 21.7
    miles.
    ¶ 23   Accordingly, Mr. Kennedy opined that Shanks’s cell phone
    could have connected to any tower within a service area of
    approximately twenty-one miles and that Shanks could have been
    12
    at a family gathering eighteen miles southeast of the tower nearest
    the victim’s home when his phone pinged that tower. However, on
    cross-examination, Mr. Kennedy conceded the 21.7-mile coverage
    area decreases in urban areas and cell towers in the Denver metro
    area would have a more limited coverage area, possibly one to one
    and a half miles.
    ¶ 24   Finally, to rebut Mr. Kennedy’s opinions, the prosecution
    offered special agent Scott Eicher, who is a founding member of the
    FBI’s Cellular Analysis Survey Team, as an expert in “historical cell
    site data analysis.” Agent Eicher agreed with Ms. Battan and Mr.
    Kennedy that a cell phone generally selects a tower based on signal
    strength and signal quality. He further testified that, although the
    maximum range of a cell tower may be twenty-one miles, in urban
    areas, the cell towers are placed in close proximity and are designed
    so that the signal does not go past the next tower. In other words,
    even in the Denver suburbs, a cell phone must be within a mile or
    mile and a half of a cell tower to use it. According to Agent Eicher,
    it was not feasible for Shanks’s phone to be eighteen miles away
    from the tower with which it was connecting. Even so, Agent Eicher
    13
    admitted that only the general location of a phone can be discerned
    from the tower and sector data, not the phone’s exact location.
    D.   Analysis
    ¶ 25    Shanks argues the district court erred in admitting Ms.
    Battan’s and Agent Eicher’s testimony without first holding a
    Shreck hearing because their opinions (1) were based on the faulty
    assumption that a cell phone always connects to the nearest tower;
    and (2) were based on unreliable science and methodology.
    1.   The Opinions Were Not Based on the Faulty Assumption that
    a Cell Phone Always Connects to the Nearest Tower
    ¶ 26    We reject Shanks’s first argument — that the prosecution’s
    experts’ opinions should not have been admitted because they were
    based on the faulty premise that a cell phone always connects to
    the closest tower — because it is inconsistent with the record.
    During pretrial arguments concerning Shanks’s request for a
    Shreck hearing, the prosecution represented to the district court
    that Ms. Battan would not opine that a cell phone necessarily
    connects to the nearest cell tower. Consistent with that
    representation, neither Ms. Battan nor Agent Eicher so testified at
    trial. Instead, both experts testified that a phone will connect with
    14
    the tower emitting the strongest, clearest signal. Neither expert’s
    opinion was based on the alleged faulty premise Shanks identifies.
    2.   The Opinions Were Based on Reliable Methodology
    ¶ 27   According to Shanks, Ms. Battan’s and Agent Eicher’s
    opinions were based on unreliable science and methodology
    because they relied on a theory called “granulization.” To
    understand Shanks’s argument, it is necessary to provide some
    background on the use of historical cell site data and its general
    acceptance nationwide.
    ¶ 28   “Historical cell-site analysis uses cell phone records and cell
    tower locations to determine, within some range of error, a cell
    phone’s location at a particular time.” United States v. Hill, 
    818 F.3d 289
    , 295 (7th Cir. 2016) (citing Aaron Blank, The Limitations
    and Admissibility of Using Historical Cellular Site Data to Track the
    Location of A Cellular Phone, 
    18 Rich. J.L. & Tech. 3
    , 5 (2011)).
    Essentially, a cell phone is a two-way radio that uses a cellular
    network to communicate. 
    Id.
     Each cell site or tower has a limited
    geographic range, which depends on the number and height of the
    antennas on the cell site, topography of the surrounding land, and
    natural and manmade obstructions. 
    Id.
    15
    ¶ 29   “In urban areas, cell towers may be located every one-half to
    one mile, while cell sites in rural areas may be three to five miles
    apart.” 
    Id.
     A cell phone generally connects to the tower with the
    strongest signal, although adjoining towers may provide coverage
    overlap. 
    Id.
     There are several factors that determine which tower a
    cell phone will connect with, including proximity, geography,
    topography, environmental factors, the technical characteristics of
    the relevant phone, and the number, height, and angle of antennas
    on the tower. See id. at 295-96; State v. Johnson, 
    797 S.E.2d 557
    ,
    561-62 (W. Va. 2017).
    ¶ 30   “A cellphone generates ‘historical’ cell-site data when it places
    a call and connects to a specific cell tower.” United States v.
    Reynolds, 626 F. App’x 610, 614-15 (6th Cir. 2015). Phone
    companies maintain call detail records, which include data about
    the duration of the call and the tower and sector to which the cell
    phone connected. See id. at 615; United States v. Jones, 
    918 F. Supp. 2d 1
    , 5 (D.D.C. 2013); United States v. Eady, No. 2:12-CR-
    00415-DCN-3, 
    2013 WL 4680527
    , at *3 (D.S.C. Aug. 30, 2013)
    (unpublished opinion). In addition, the cell service providers
    maintain a list of the precise location of each tower and the
    16
    specifications for each of the sectors of the tower. See Jones, 918 F.
    Supp. 2d at 5.
    ¶ 31   Typically, in criminal cases, the prosecution offers a witness
    who uses these resources to plot on a map the location of the cell
    tower used by an individual’s cell phone for a call or series of calls.
    See, e.g., United States v. Machado-Erazo, 
    950 F. Supp. 2d 49
    , 54
    (D.D.C. 2013); Jones, 918 F. Supp. 2d at 4-5; Eady, 
    2013 WL 4680527
    , at *3; United States v. Davis, No. 11-60285-CR, 
    2013 WL 2156659
    , at *5 (S.D. Fla. May 17, 2013) (unpublished opinion).
    Often, these witnesses also will plot the specific sector to which the
    individual’s phone connected by drawing lines coming out from
    each tower at a 120-degree angle. See Machado-Erazo, 950 F.
    Supp. 2d at 54; Jones, 918 F. Supp. 2d at 3; Eady, 
    2013 WL 4680527
    , at *3; Davis, 
    2013 WL 2156659
    , at *5. From these maps,
    the witness may opine that the individual’s phone was likely within
    a general geographic location, see Jones, 918 F. Supp. 2d at 5, or
    the coverage area of a particular sector, see Eady, 
    2013 WL 4680527
    , at *3, at the time of each call.
    ¶ 32   Federal courts “that have been called upon to decide whether
    to admit historical cell-site analysis have almost universally done
    17
    so.” Hill, 818 F.3d at 297 (collecting cases); Machado-Erazo, 950 F.
    Supp. 2d at 56 (collecting cases). Several state courts have done
    the same. See, e.g., People v. Fountain, 
    62 N.E.3d 1107
    , 1124-25
    (Ill. App. Ct. 2016) (collecting cases). And a number of these courts
    have concluded that the methodology described above is widely
    accepted as reliable and may be admitted without first holding an
    evidentiary hearing. See, e.g., Hill, 818 F.3d at 298; Jones, 918 F.
    Supp. 2d at 4-5; Fountain, 62 N.E.3d at 1124-25; Commonwealth v.
    Nevels, 
    203 A.3d 229
    , 241 (Pa. Super. Ct. 2019). In so doing,
    however, these courts have distinguished the use of historic cell site
    data to determine the general location of a phone from the theory of
    “granulization,” which purports to identify a caller’s specific
    location. See United States v. Evans, 
    892 F. Supp. 2d 949
    , 956-57
    (N.D. Ill. 2012).
    ¶ 33   The theory of “granulization” was rejected by the United States
    District Court for the Northern District of Illinois in Evans, on
    which Shanks heavily relies. Although Evans does not define
    “granulization,” the court explained that the theory requires an
    expert to identify
    18
    (1) the physical location of the cell sites used
    by the phone during the relevant time period;
    (2) the specific antenna used at each cell site;
    and (3) the direction of the antenna’s coverage.
    He then estimates the range of each antenna’s
    coverage based on the proximity of the tower to
    other towers in the area. This is the area in
    which the cell phone could connect with the
    tower given the angle of the antenna and the
    strength of its signal. Finally, using his
    training and experience, [the expert] predicts
    where the coverage area of one tower will
    overlap with the coverage area of another.
    Id. at 952. Using this theory, the prosecution in Evans sought to
    prove that the defendant was in the same building where the
    kidnapping victim was held for ransom because the building fell
    squarely within the coverage overlap of two towers used by the
    defendant’s phone to make calls during a relevant time period. Id.
    ¶ 34   The court identified two flaws with the theory of granulization:
    (1) it assumes that a cell phone uses the tower closest to it at the
    time of a call, without accounting for the possibility that the phone
    might have connected to other towers based on a variety of factors;
    and (2) it remains wholly untested by the scientific community. Id.
    at 956. Although the court acknowledged that certain types of
    historical cell site analysis are reliable and admissible, it rejected
    19
    the use of granulization theory to pinpoint the defendant’s location.
    Id. at 953, 955, 957.
    ¶ 35   Having considered the foregoing cases, we hold that the use of
    historical cell site data to determine the general geographic location
    of a cell phone is widely accepted as reliable and does not require a
    Shreck hearing. Accordingly, we conclude the district court did not
    abuse its discretion by denying Shanks’s request for a Shreck
    hearing.
    ¶ 36   We further conclude that the evidence presented at trial was
    within the bounds of reliable historical cell site analysis. The
    prosecution experts generally explained how cell towers work and
    identified the variables and limitations incorporated into their
    analyses. Ms. Battan mapped the cell towers, identified which of
    Shanks’s calls used which towers and sectors, and opined — when
    asked on cross-examination — that it was not possible for Shanks’s
    phone to be eighteen miles away from a tower to which it
    connected.
    ¶ 37   Agent Eicher testified that he had reviewed Ms. Battan’s
    analysis and agreed with it. He further opined, based on the
    approximate coverage area of cell towers in the Denver metro area,
    20
    that it was not feasible for Shanks’s phone to be eighteen miles
    away at the time of the offense.
    ¶ 38   Importantly, neither expert opined about coverage overlap
    between towers or that a cell phone necessarily connects to the
    closest tower. Neither expert opined as to the precise location of
    Shanks’s phone at any specific time.
    ¶ 39   Shanks takes issue with how Ms. Battan portrayed the cell
    tower sectors on her map and how Agent Eicher estimated the
    range of cell towers in the Denver metro area. Shanks also argues
    that the prosecution experts failed to consider the many variables
    affecting how a cell phone and tower connect.
    ¶ 40   But to the extent either expert’s opinion was based on
    assumptions about coverage range or fails to account for certain
    variables, any challenges to those assumptions or to the expert’s
    application of variables went to the weight of the evidence, not its
    admissibility. See Jones, 918 F. Supp. 2d at 5 (“[T]o the extent that
    Agent Eicher’s testimony relies on assumptions about the strength
    of the signal from a given cell tower, any challenges to those
    assumptions go to the weight of his testimony, not its reliability.”).
    Indeed, while assumptions and variables may be tested by vigorous
    21
    cross-examination, they do “not render the fundamental
    methodology of cell site analysis unreliable.” Id.; see also United
    States v. Pembrook, 
    119 F. Supp. 3d 577
    , 597-98 (E.D. Mich. 2015)
    (“[T]o the extent that [the witness] has made assumptions about
    signal strength that call into question his estimate of where the
    phones were located at particular times, Defendants can test those
    assumptions on cross exam.”).
    ¶ 41   Here, both prosecution experts were subject to thorough
    cross-examination. Shanks also offered his own expert to challenge
    the accuracy of the prosecution’s evidence. That the experts
    disagreed did not undermine the reliability of the evidence or
    counsel against its admission in the first place. See Campbell, ¶ 42.
    ¶ 42   Thus, we also conclude that the district court did not abuse its
    discretion by admitting Ms. Battan’s and Agent Eicher’s testimony.
    III.   Identification Evidence
    ¶ 43   Shanks contends that the district court erred by denying his
    motion to suppress the victim’s out-of-court identification.
    According to Shanks, the court further erred by admitting the
    victim’s in-court identification, which was based on the
    22
    impermissibly suggestive out-of-court identification. We disagree
    with both contentions.
    A.        Standard of Review
    ¶ 44   “The ultimate question as to the constitutionality of pretrial
    identification procedures is a mixed question of law and fact.”
    Bernal v. People, 
    44 P.3d 184
    , 190 (Colo. 2002). Thus, “[w]hen
    reviewing a trial court’s denial of a motion to suppress, we generally
    defer to the trial court’s factual findings, but review its legal
    conclusions de novo.” People v. Plancarte, 
    232 P.3d 186
    , 189 (Colo.
    App. 2009). But while the trial court’s findings of historical fact are
    entitled to deference, “an appellate court may give different weight
    to those facts and may reach a different conclusion in light of the
    legal standard.” Bernal, 44 P.3d at 190; see People v. Singley, 2015
    COA 78M, ¶ 9.
    B.    Applicable Law
    ¶ 45   To determine the admissibility of an out-of-court photographic
    identification, the court must engage in a two-step analysis. First,
    the defendant must prove that the identification procedure was
    impermissibly suggestive. Bernal, 44 P.3d at 191; Singley, ¶ 14. If
    the defendant fails to meet this initial burden, no further inquiry is
    23
    required and the identification is admissible. Bernal, 44 P.3d at
    191 (“It is important to note that these two steps must be completed
    separately; it is only necessary to reach the second step if the court
    first determines that the array was impermissibly suggestive.”);
    Singley, ¶ 14.
    ¶ 46   Second, if the court finds the photo array impermissibly
    suggestive, the burden shifts to the prosecution to show that the
    identification was nonetheless reliable under the totality of the
    circumstances. Bernal, 44 P.3d at 192; see also Singley, ¶ 15. “As
    long as the totality of the circumstances does not indicate a very
    substantial likelihood of irreparable misidentification, no
    constitutional impediment to the admission of the identification
    testimony exists.” Bernal, 44 P.3d at 192.
    ¶ 47   But a “defendant is denied due process when an in-court
    identification is based upon an out-of-court identification which is
    so suggestive as to render the in-court identification unreliable.”
    People v. Borghesi, 
    66 P.3d 93
    , 103 (Colo. 2003).
    ¶ 48   In determining whether the pretrial photo identification
    procedure is impermissibly suggestive, the court may consider such
    relevant factors as “the size of the array, the manner of its
    24
    presentation by the officers, and the details of the photographs
    themselves.” Bernal, 44 P.3d at 191. The size of the array is a
    factor affecting the weight a court gives to any irregularities. Id.
    Thus, the more pictures used, the less likely it is that a minor
    difference will have a prejudicial effect; the fewer pictures used, the
    closer the array must be scrutinized. Id.
    ¶ 49   The crucial question when examining the array itself is
    “whether the picture of the accused, which matches descriptions
    given by the witness, so stood out from all of the other photographs
    as to ‘suggest to an identifying witness that that person was more
    likely to be the culprit.’” Id. (quoting Jarerett v. Headley, 
    802 F.2d 34
    , 41 (2d Cir. 1986)). “In other words, the array must not be so
    limited that the defendant is the only one to match the witness’s
    description of the perpetrator.” 
    Id.
     The array need not include
    exact replicas of the defendant or be uniform with respect to a given
    characteristic, but they must be “matched by race, approximate
    age, facial hair, and a number of other characteristics.” Id. at
    191-92 (quoting People v. Webster, 
    987 P.2d 836
    , 839 (Colo. App.
    1998)). An array that includes a photo “unique in a manner directly
    related to an important identification factor” may be impermissibly
    25
    suggestive. Id. at 192; see also Grubbs v. Hannigan, 
    982 F.2d 1483
    ,
    1490 (10th Cir. 1993) (“Although a photo-lineup is not necessarily
    suggestive merely because the individuals in the lineup differ in
    facial characteristics, . . . here the differences were either strikingly
    apparent, such as a swollen eye, or they related to an important
    component of [the victim’s] description of her assailant, his hair
    style.”).
    ¶ 50    We are in the same position as the district court to review the
    details of the photographs and consider their placement in the
    array. Thus, we review de novo whether the photographic array
    itself was impermissibly suggestive. See People v. Carlos, 
    41 Cal. Rptr. 3d 873
    , 876 (Cal. Ct. App. 2006) (reviewing the suggestibility
    of a photo array de novo); McCoy v. United States, 
    781 A.2d 765
    ,
    771 (D.C. 2001) (same); Gamboa v. State, 
    296 S.W.3d 574
    , 581
    (Tex. Crim. App. 2009) (“We review de novo a trial court’s ruling on
    how the suggestiveness of a pre-trial photo array may have
    influenced an in-court identification.”); cf. People v. Ramadon, 
    2013 CO 68
    , ¶ 21 (“When the interrogation is audio or video-recorded,
    and there are no disputed facts outside the recording pertinent to
    the suppression issue, we are in the same position as
    26
    the trial court in determining whether the statements should or
    should not be suppressed under the totality of the circumstances.”).
    C.   Analysis
    ¶ 51   The victim described the second assailant as a “black Abe
    Lincoln” because he had “an Abe Lincoln style beard on his chin
    and high cheek bones.” The photo array presented to him
    contained pictures of six men arranged in two rows of three, with
    Shanks appearing in the middle of the bottom row. The men all
    appear to be African-American, though one man (not Shanks) has
    noticeably lighter skin than the other five. They all have similarly
    placed cheekbones, close-shaven haircuts, and some facial hair. 3
    They all appear to be of similar age. Officers presented the array in
    black-and-white, so there is no drastic difference in background
    color, lighting, or clothing color. All men appear to be wearing
    prison clothing. Each photograph is only of the head and neck and
    reveals nothing of the height or weight of the men.
    3 None of the men have particularly bushy sideburns or beards,
    which typically are associated with Abraham Lincoln. However, at
    trial, the victim testified that he used the description “black
    Abraham Lincoln” in reference to the $5 bill, which depicts Lincoln
    with closely-trimmed facial hair. In any event, Shanks’s facial hair
    does not distinguish him from the others in the photo array.
    27
    ¶ 52   Shanks points out that he is the only one with a pointy head,
    that he has small ears, and that his nose is broader than the rest.
    We agree that none of the other men have heads as pointy as
    Shanks’s or a nose that is quite as broad; however, several of the
    men do have long, slender faces and small ears, and their noses are
    a range of sizes. Further, the victim did not describe his assailant
    as having a pointy head, small ears, or a broad nose, so these are
    not defining characteristics that create impermissible
    suggestiveness. See Borghesi, 66 P.3d at 105; Bernal, 44 P.3d at
    192; People v. Owens, 
    97 P.3d 227
    , 233 (Colo. App. 2004).
    ¶ 53   Thus, we conclude that the photo array itself was not
    impermissibly suggestive and that the district court did not abuse
    its discretion by admitting it. Because we have concluded that the
    photo array was not impermissibly suggestive, we need not
    determine whether the identification was otherwise reliable under
    the totality of the circumstances.
    ¶ 54   Further, we conclude that the victim’s subsequent in-court
    identification of Shanks was not inherently unreliable. As noted,
    the in-court identification was not preceded by an impermissibly
    suggestive pretrial identification procedure, and there was nothing
    28
    suggestive about the in-court identification beyond the normal
    courtroom setting. See Garner v. People, 
    2019 CO 19
    , ¶ 5. Defense
    counsel was able to cross-examine the victim about the
    identification during the trial and to highlight for the jury any
    factors he believed made the in-court identification suggestive. See
    id. at ¶ 55. Thus, we also conclude that the district court did not
    err by admitting the in-court identification.
    IV.    Alternate Suspect Defense
    ¶ 55   Shanks contends that the district court violated his rights to
    due process, to present a defense, and to a fair trial by denying his
    alternate suspect defense. We disagree.
    A.   Standard of Review
    ¶ 56   We review the trial court’s evidentiary decisions, including
    whether to admit alternate suspect evidence, for an abuse of
    discretion. People v. Folsom, 2017 COA 146M, ¶ 29. A trial court
    abuses its discretion where its decision is manifestly arbitrary,
    unreasonable, or unfair, or “is based on an erroneous view of the
    law.” People v. Elmarr, 
    2015 CO 53
    , ¶ 20.
    29
    B.    Applicable Legal Principles
    ¶ 57   A defendant has a constitutional right to present a defense,
    including the right to present evidence that someone other than the
    defendant may have committed the crime, because “a criminal
    defendant is entitled to all reasonable opportunities to present
    evidence that might tend to create doubt as to [his] guilt.” Folsom,
    ¶ 30 (quoting Elmarr, ¶ 26). To be admissible, however, the
    alternate suspect evidence must be relevant and its probative value
    must not be substantially outweighed by “the danger of unfair
    prejudice, confusion of the issues, or misleading the jury, or by
    considerations of undue delay, waste of time, or needless
    presentation of cumulative evidence.” CRE 403; see Elmarr, ¶ 27.
    Relevant evidence is evidence “having any tendency to make the
    existence of any fact that is of consequence to the determination of
    the action more probable or less probable than it would be without
    the evidence.” CRE 401.
    ¶ 58   “[T]he admissibility of alternate suspect evidence ultimately
    depends on the strength of the connection between
    the alternate suspect and the charged crime.” Elmarr, ¶ 22; accord
    Folsom, ¶ 31. The “evidence must create more than just an
    30
    unsupported inference or possible ground for suspicion.” Elmarr,
    ¶ 32. Instead, the evidence must establish a “non-speculative
    connection or nexus between the alternate suspect and the crime
    charged.” 
    Id.
     Whether the requisite connection exists requires a
    case-by-case analysis considering all evidence proffered by the
    defendant to show that the alternate suspect committed the crime.
    
    Id.
    ¶ 59    The Colorado Supreme Court has held on numerous occasions
    that merely showing that an alternate suspect had the motive or the
    opportunity to commit the charged offense, without some additional
    proof connecting the alternate suspect to the offense, is insufficient
    to prove that necessary nexus. E.g., id. at ¶ 34 (“[E]vidence merely
    showing that someone else had a motive or opportunity to commit
    the charged crime — without other additional evidence
    circumstantially or inferentially linking the alternate suspect to the
    charged crime — presents too tenuous and speculative a connection
    to be relevant because it gives rise to no more than grounds for
    possible suspicion.”); People v. Mulligan, 
    193 Colo. 509
    , 518, 
    568 P.2d 449
    , 456-57 (1977) (same).
    31
    C.   Additional Background
    ¶ 60   Before trial, Shanks endorsed an alternate suspect defense,
    asserting that a man named Andrew Davis was the second
    assailant. Shanks’s endorsement stated the following:
    • Davis and Eastman were “associated” at the time of the
    offense;
    • Davis was at liberty and lived in the area of the offense at
    the time and therefore had the opportunity to commit it;
    • Eastman did not approve of Shanks’s relationship with
    her mother and the two had never gotten along;
    • Davis was associated with a gray Volkswagon Jetta and a
    witness described the car that dropped Cody off just after
    the offense as a gray Jetta;
    • Davis’s physical appearance more closely resembled the
    description given by the victim; and
    • Davis had an extensive criminal history involving
    menacing, weapons, and home invasions.
    ¶ 61   The prosecution moved to strike the endorsement and
    preclude Shanks from presenting alternate suspect evidence at
    32
    trial, arguing that the facts alleged were speculative and irrelevant
    to the charged offense. The court granted the prosecution’s motion.
    ¶ 62   At the beginning of trial, after it had become clear that
    Eastman would testify, defense counsel again asked for permission
    to introduce alternate suspect evidence. Counsel represented to the
    district court that Eastman had recently told her mother that Davis
    committed the crime with her and Cody, not Shanks.
    ¶ 63   The district court still found that the proffered evidence was
    not alternate suspect evidence and that there was “no actual
    connection” between Davis and the charged offense. The court did
    conclude, however, that the evidence could be used for
    impeachment, depending on Eastman’s testimony at trial. The
    court said that defense counsel could question Eastman about her
    relationship with Davis, about her covering up for him and lying to
    investigators, and about her dislike of Shanks. In addition, counsel
    likely would be allowed to introduce the photographs of Davis.
    ¶ 64   At trial, Eastman denied telling her mother that Davis helped
    commit the offense. She also testified that she was not dating Davis
    at the time. Her mother testified to the contrary and was shown
    pictures of Davis, which she confirmed accurately reflected his
    33
    appearance at that time. For reasons not pertinent to our analysis,
    no photographs of Davis were admitted at trial. Still, the court told
    defense counsel that he could argue in closing that Davis was an
    alternate suspect. Ultimately, counsel did not do so.
    D.   Analysis
    1.   The District Court Did Not Abuse Its Discretion
    ¶ 65   The evidence Shanks first presented to the district court in
    support of his endorsement of an alternate suspect, even
    considered collectively, was speculative and did not provide a direct
    nexus between Davis and the offense. Generally, it demonstrated
    that Davis lived nearby at the time and was potentially dating one of
    the codefendants, thereby providing him the opportunity to commit
    the offense. But no one identified Davis as being involved in the
    offense, there was no physical evidence linking him to the offense,
    there was no evidence of a motive for him to commit the offense,
    there was no evidence about factual similarities between this
    offense and his previous crimes, and the victim confidently
    identified Shanks as the assailant. See Elmarr, ¶ 30 (“A defendant .
    . . suggesting that an alternate suspect committed the crime . . .
    might seek to show that someone else: had a motive to commit the
    34
    crime; had an opportunity to commit the crime; confessed to the
    crime or otherwise engaged in behavior indicating his involvement;
    is linked to physical evidence of the crime; or committed similar
    acts or crimes.”); Owens, 
    97 P.3d at 235
     (affirming trial court’s
    exclusion of evidence that raised speculation but provided no
    “direct connection” between the alternate suspect and the crime);
    People v. Perez, 
    972 P.2d 1072
    , 1074-75 (Colo. App. 1998) (rejecting
    alternate suspect evidence based on commission of a similar crime
    when the evidence did not “indicat[e] any distinctive similarities in
    the details of the crimes”); cf. Folsom, ¶¶ 38-40 (reversing trial
    court’s exclusion of evidence that an alternate suspect, among other
    things, had been convicted of a similar crime in the same
    geographic area; had been linked to numerous other incidents in
    the area in the same general timeframe, including at least three
    incidents at the victim’s house; was identified by the victim as a
    person she recognized; and more closely matched the victim’s
    description than did the defendant).
    ¶ 66   And although Shanks told the district court on the morning of
    trial that Eastman would provide a direct link between Davis and
    the crime, Eastman actually testified that Davis was not involved
    35
    and denied that she had ever told her mother that Davis was
    involved. Thus, the evidence created nothing more than “an
    unsupported inference or possible ground for suspicion” that Davis
    committed the charged crimes. Under these circumstances, the
    district court did not abuse its discretion.
    2.    Any Error by the District Court Was Harmless
    ¶ 67   Even if we were to assume the district court erred by
    precluding certain alternate suspect evidence, we conclude that any
    such error was harmless. An evidentiary error precluding a
    defendant from presenting evidence may be of constitutional
    magnitude “only where the defendant was denied virtually his [or
    her] only means of effectively testing significant prosecution
    evidence.” People v. Brown, 2014 COA 155M-2, ¶ 6
    (quoting Krutsinger v. People, 
    219 P.3d 1054
    , 1062 (Colo. 2009)).
    Otherwise, reversal is required only if the error “substantially
    influenced the verdict or affected the fairness of the trial.” Brown, ¶
    6; see also Elmarr, ¶ 27 (“[T]he right to present a defense is
    generally subject to, and constrained by, familiar and well-
    established limits on the admissibility of evidence.”).
    36
    ¶ 68   Here, the district court did not preclude defense counsel from
    mentioning Davis or arguing his theory of defense that this was a
    case of mistaken identity. Defense counsel was still permitted to,
    and in fact did, attack Eastman’s credibility by questioning her and
    her mother about Davis’s involvement with Eastman and Eastman’s
    alleged statements to her mother that Davis was the second
    assailant. Thus, despite not receiving a jury instruction on
    alternate suspect evidence, the jury had before it sufficient evidence
    and argument to understand Shanks’s defense.
    ¶ 69   Accordingly, even if the district court erred in denying Shanks
    his alternate suspect defense, the error was harmless.
    V.    Use of Nickname
    ¶ 70   Shanks contends the district court erred by admitting
    references to his nickname, “Capone,” which created unfair
    prejudice because the name is a “gang name.” We disagree.
    A.   Preservation and Standard of Review
    ¶ 71   The parties disagree as to whether this claim of error was
    preserved and what standard of review should apply. Shanks
    contends it was preserved by defense counsel’s objection to the
    prosecutor’s use of “Capone” as his “moniker” or “alias.” As the
    37
    transcript reveals, defense counsel suggested that the prosecutor
    use the word “nickname” instead of “moniker” or “alias,” the
    prosecutor revised his question accordingly, and the district court
    never ruled on the objection. Defense counsel did not otherwise
    object to the use of the nickname “Capone” throughout the balance
    of the trial.
    ¶ 72    We review a trial court’s decision to admit evidence for an
    abuse of discretion. People v. Clark, 
    2015 COA 44
    , ¶ 14. If the
    alleged evidentiary error is unpreserved, we reverse only if the error
    was plain. Hagos v. People, 
    2012 CO 63
    , ¶ 14. Plain errors are
    those that are obvious and substantial and so undermine the
    fundamental fairness of the trial itself as to cast serious doubt on
    the judgment of conviction. 
    Id.
     Because we find the district court
    did not abuse its discretion, we need not resolve the parties’ dispute
    regarding preservation.
    B.    Analysis
    ¶ 73    “[B]ecause ‘gangs are regarded with considerable disfavor by
    our society,’ gang-related evidence must be ‘admitted with care.’”
    Clark, ¶ 16 (quoting People v. Trujillo, 
    2014 COA 72
    , ¶ 72). Here,
    however, no evidence was presented that Shanks was in a gang,
    38
    that his nickname was affiliated with a gang, or that this offense
    was gang-related. Indeed, the word “gang” was not used once in
    front of the jury during trial. The only reason the nickname was
    used was because that is the name by which most of the witnesses
    knew Shanks. In fact, some of the witnesses did not even know his
    real name. And the prosecutor did not use the name as a way of
    introducing bad character evidence. It was used merely for
    identification, and to argue that the jury should discount good
    character testimony from Shanks’s family members because they
    did not even know he was nicknamed “Capone.”
    ¶ 74   Under these circumstances, we perceive no abuse of discretion
    in the district court’s decision to allow the use of the nickname.
    See People v. Samuels, 
    228 P.3d 229
    , 243 (Colo. App. 2009).
    VI.   Cumulative Error
    ¶ 75   Lastly, Shanks contends that the cumulative effect of the
    errors raised in this appeal warrant reversal. We disagree.
    ¶ 76   “We will reverse for cumulative error where, although
    numerous individual allegations of error may be deemed harmless
    and not require reversal, in the aggregate those errors show
    prejudice to the defendant’s substantial rights and, thus, the
    39
    absence of a fair trial.” People v. Stewart, 
    2017 COA 99
    , ¶ 39
    (quoting People v. Gallegos, 
    260 P.3d 15
    , 28-29 (Colo. App. 2010));
    see People v. Mendenhall, 2015 COA 107M, ¶ 82. However, for the
    doctrine to apply, numerous errors must have been committed, not
    merely alleged. People v. Allgier, 
    2018 COA 122
    , ¶ 70.
    ¶ 77   Having found no errors, we reject this contention.
    VII. Conclusion
    ¶ 78   The judgment is affirmed.
    JUDGE FURMAN and JUDGE DAVIDSON concur.
    40