MCALESTER, OKLA. -- Lawyers failed for the sixth time to win a Supreme Court stay for a man scheduled for execution early today for killing a man who walked in on a burglary.

It would be Oklahoma's first execution in 24 years.

Charles Troy Coleman, 43, was to be put to death by lethal injection at 12:02 a.m. at Oklahoma State Penitentiary. He was sentenced to die for the 1979 shotgun slaying of John Seward in Muskogee.

Seward, 68, and his wife, Roxie, 62, were killed when they surprised a burglar at a relative's home. Coleman was not tried in Roxie Seward's death.

Coleman's truck was seen at the home, and custom-cut meat and other possessions from the house were found in his truck when he was arrested.

The U.S. Supreme Court on Sunday refused to block Coleman's execution, the sixth time it had turned him down. Public Defender Mandy Welch raised mental competency questions in seeking a stay of execution.

Within hours of that setback, attorneys for Coleman lost their second appeal in as many days with the U.S. 10th Circuit Court of Appeals in Denver.

They conceivably could go back to the Supreme Court with an appeal of that federal appeals court ruling, spokesman Gerald Adams of the Oklahoma attorney general's office said.