BONNE TERRE, Mo (News First) – An evidentiary hearing in Missouri will determine the fate of a man on death row who thought DNA evidence uncovered in his case was enough to save him. A decades-old mistake by a prosecutor’s office has kept Marcellus Williams’ life hanging in the balance. The 55-year-old is scheduled to be executed at the prison in Bonne Terre on September 24th for the 1998 stabbing death of Lisha Gayle in suburban St. Louis. A judge on Wednesday presided over a hearing challenging Williams’ guilt but the key piece of evidence to support Williams is DNA testing that is no longer viable. That’s because testing revealed the murder weapon was mishandled by the St. Louis County prosecutor’s office more than two decades ago.