SIOUX FALLS, S.D. (AP) – A man who stabbed to death a former co-worker who interrupted him during a burglary is set to be executed at 1:30 this afternoon in South Dakota barring a last-minute stay.

Charles Russell Rhines brushed off a plea for mercy from 22-year-old Donnivan Schaeffer in the 1992 murder at a Rapid City doughnut shop.

Now 63, Rhines unsuccessfully challenged the execution drug the state plans to use in today’s execution in Sioux Falls. He’s appealing that ruling to the state Supreme Court.

Rhines has also asked the U.S. Supreme Court to block his execution. He argues that the jury that sentenced him to death had an anti-gay bias. He also argues that the state hasn’t allowed him to be examined for cognitive and psychiatric impairments.