The Missouri Supreme Court and Gov. Mike Parson have declined to halt Tuesday’s execution of a death row inmate prosecutors say may be innocent, leaving his fate in the hands of the US Supreme Court with less than 24 hours to go before he is scheduled to die by lethal injection.

The Missouri Supreme Court will hear arguments as attorneys working on behalf of Marcellus Williams seek to save him, just a day before his scheduled execution

County prosecutors and defense lawyers both claim that mishandled evidence and racial bias tainted the murder case. Marcellus Williams is slated for execution Sept. 24 at 6 p.m. CT.