OKLAHOMA CITY, OK - The state Pardon and Parole Board denied clemency Tuesday for a 74-year-old death row inmate, clearing the way for him to become the oldest person ever executed in Oklahoma.

The five-member board voted 5-0 to deny clemency for John Albert Boltz, who was sentenced to die for the murder of his 23-year-old stepson 22 years ago, said Emily Lang, spokeswoman for Attorney General Drew Edmondson's office. Boltz is scheduled to die by lethal injection on June 1 at the Oklahoma State Penitentiary at McAlester.

The oldest inmate ever put to death in Oklahoma is Robert Hendricks, 64, who was executed in 1957, said Jerry Massie, spokesman for the Oklahoma Department of Corrections. Hendricks was convicted of murder in Craig County, Massie said.

Boltz was convicted of first-degree murder for the April 18, 1984, murder of Doug Kirby, who was stabbed eleven times after he confronted Boltz about threats Boltz had made to Kirby's mother, Pat Kirby, authorities said. Pat Kirby had told Boltz she wanted a divorce earlier that day.

During his trial, Boltz argued he acted in self-defense. He said Kirby came to his Pottawatomie County home to confront him.

Boltz repeated those assertions Tuesday during a presentation via electronic teleconference from a cell at OSP to the board's meeting at the Hillsdale Community Correction Center in Oklahoma City, Lang said. Kirby's father and two brothers opposed the clemency request.

Edmondson's office also opposed the request, arguing that Kirby's death was especially heinous and cruel and has had a devastating affect on his family, including Kirby's son, Nathan Kirby, who was just four years old when his father was killed.

The Medical Examiner's Office said Kirby sustained eight separate stab wounds to the chest and abdomen as well as cutting wounds of the neck that nearly decapitated him.