A St. Louis County, Missouri, judge upheld the murder conviction of Marcellus Williams, ruling that a prosecutor who contaminated key evidence by handling it without wearing gloves before Williams’s trial had not acted in “bad faith,” but instead was merely following his normal procedure.

Williams maintains his innocence in the killing. No crime scene evidence linked him to the murder inside Picus’s home, and Williams long argued that testing of the weapon used to kill Picus could prove he was innocent. The trial judge denied his attorneys’ request to test the knife for DNA before trial, and he was convicted in 2001 based on the questionable testimony of two informants. DNA testing done in 2016, however, revealed unknown genetic material on the knife’s handle.

Based in part on the unidentified DNA, Bell filed a motion in January to vacate Williams’s conviction, invoking a relatively new Missouri law that allows elected prosecutors in the state to undo convictions they believe their offices wrongly obtained. The court was scheduled to hold an evidentiary hearing on the case, where a special-appointed counsel was slated to argue that Williams should be freed. Yet additional testing on the knife revealed at the last minute that neither Larner nor his investigator could be excluded as the source of the unknown DNA. In other words, whatever crime scene DNA might have been on the knife was irrevocably lost by the prosecution team’s handling of it before Williams’s trial.

Rojo Bushnell, of the Midwest Innocence Project, said Williams’s legal team would continue to seek relief via the courts and Gov. Mike Parsons, who could grant clemency. “We will continue pursuing every possible option to prevent Mr. Williams’s wrongful execution,” she said in her statement. “There is still time … to ensure that Missouri does not commit the irreparable injustice of executing an innocent person.”