SIOUX FALLS, S.D. (AP) – The South Dakota Supreme Court has rejected an appeal by a state prison scheduled to die by lethal injection today for the murder of a former co-worker.

Charles Russell Rhines argued that the state’s choice of drug to be used in his lethal injection does not meet the requirement of being “ultra-short-acting” that was in effect at the time of his conviction.

A circuit judge last week rejected his argument, writing that the pentobarbital South Dakota will use works as fast or faster as other drugs cited by Rhines when used in lethal doses.

The state’s high court agreed.

Rhines immediately appealed that ruling to the U.S. Supreme Court, which already has an appeal by Rhines on other grounds.