The Florida Supreme Court refused to grant a stay of execution for John Richard Marek, a convicted murderer scheduled to be put to death by lethal injection at 6 p.m. today.

Marek and Raymond Wigley were convicted of kidnapping, raping and murdering Adela Marie Simmons in 1983 when her car broke down on the turnpike near Stuart.

Marek has another appeal pending before the U.S. Supreme Court. A circuit court judge on Monday also denied another hearing to Marek, who claims that Wigley killed Simmons. Wigley was sentenced to life while Marek received the death penalty. Marek’s lawyers argue that he, too, should be serving life in prison.

Marek has spent more than two decades on Florida’s Death Row. Gov. Charlie Crist ordered him to be put to death in May but the Supreme Court halted that. If the execution takes place today, Marek will be the fourth Death Row inmate to be executed since Crist took office in 2007.