that: defendant’s knowing, intelligent, and voluntary guilty plea waived any right to test the chain of custody of the drug evidence.7 (6) In this case, McMillan admitted that he was guilty of Trafficking in Cocaine and Tampering with Evidence.8 As we recognized in affirming the dismissal of McMillan’s first motion for postconviction relief, McMillan’s guilty plea was knowing and voluntary? McMillan is therefore bound by the statements he made to the Superior Court before his plea was accepted and he is prevented from reopening his case to make claims that do not address his guilt and involve 1.10 impeachment evidence that would only be relevant at atria By pleading guilty,