Photo: The Canadian Press

Missouri Gov. Eric Greitens on Tuesday halted the scheduled execution of condemned inmate Marcellus Williams after DNA testing raised questions about whether he actually killed.

Just hours before Williams was to be put to death, the Republican governor said in an email that he was issuing a stay of execution. Williams was convicted of fatally stabbing former St. Louis Post-Dispatch reporter Lisha Gayle during a 1998 burglary at her suburban St. Louis home. Williams was to be executed Tuesday evening.

Greitens' decision comes after Williams' attorneys cited DNA evidence found on the murder weapon that matched another unknown person, but not Williams. But St. Louis County prosecutor Bob McCulloch said there was ample other evidence to convict Williams, and that there's "zero possibility" he's innocent.

"A sentence of death is the ultimate, permanent punishment," Greitens said in his statement. "To carry out the death penalty, the people of Missouri must have confidence in the judgment of guilt."

Greitens said he will appoint a five-member board of inquiry made up of retired judges with subpoena power. The board will make a recommendation to the governor concerning whether the 48-year-old Williams should be executed. No timetable has been set.

Williams' attorney, Kent Gipson, who had asked Greitens for clemency, said the stay of execution was "the appropriate thing to do." He believes large-scale opposition to the execution was a factor in the governor's decision.

"The people have spoken," Gipson said. "This online petition had a quarter of a million signatures. The case has generated a lot of outrage all over the country and the world."