A 74-year-old man was executed Thursday for the nearly decapitating his stepson with a knife more than two decades ago.

John A. Boltz was the oldest death row inmate executed in Oklahoma and the third-oldest in the country since capital punishment was reinstated in 1977.

Officials had trouble finding a vein to inject the lethal drugs, delaying the execution for more than an hour at the Oklahoma State Penitentiary. Boltz was pronounced dead at 7:22 p.m.

Boltz was 52 when a jury convicted him of the 1984 killing. Doug Kirby, 22, had driven to Boltz's home to discuss threats Boltz had made against his estranged wife, who had asked for a divorce, authorities said.

The medical examiner said Kirby was stabbed eight times in the chest and abdomen and suffered a cut in the neck that nearly decapitated him. Boltz claimed he acted in self-defense.

Boltz blamed members of Kirby's family for his execution.

"This is a time of gladness for me and a time of sadness," he said. "It's a time of gladness because I know I'm going to a better place. It's a time of sadness because I think of all the people involved who got me here and what's in store for them."

The victim's brother, Jim Kirby; son Nathan, who was just 4 years old when his father died; and other family members called Boltz' execution "long overdue."

Earlier in the day, a federal judge issued a stay of execution after Boltz's attorney argued that Oklahoma's lethal injection protocol violated his client's rights against cruel and unusual punishment.

But a federal appeals court reversed that decision and the Supreme Court denied two requests for a stay shortly before the execution.

The oldest person put to death — age 77 — was executed in Mississippi on Dec. 14.