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.

The ruling, issued on Thursday by Circuit Court Judge Bruce Hilton, dismantles Williams’s latest attempt to prove his innocence and paves the way for his execution on September 24. “There is no basis for a court to find that Williams is innocent,” Hilton wrote. “Williams is guilty of first-degree murder, and has been sentenced to death.”