A Missouri man is scheduled to be executed on Tuesday unless the U.S. Supreme Court intervenes at the last minute, even though the prosecutor's office that secured his murder conviction 21 years ago has expressed doubts about the integrity of the case.

Missouri is set to execute 55-year-old death row inmate Marcellus Williams on Tuesday evening — despite pleas from prosecutors and even his victim’s family. Missouri’s governor, Mike Parson, and its supreme court said Monday that sufficient evidence exists for the state to take Williams’ life for the 1998 stabbing murder of Felicia Gayle,

"No jury nor court, including at the trial, appellate, and Supreme Court levels, have ever found merit in Mr. Williams' innocence claims," said Missouri Governor Mike Parson.