The Supreme Court refused to block Missouri from executing Marcellus Williams on Tuesday amid questions about the jury selection process and key evidence used in convicting him of murder in 2001.

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.

Lawyers for Marcellus Williams, who maintains his innocence, argued Monday the execution should be halted over the exclusion of a potential Black juror.