California executed its oldest condemned inmate early Tuesday for arranging a triple murder 25 years ago to silence witnesses in another killing.

Clarence Ray Allen was pronounced dead by lethal injection at 12:38 a.m. at San Quentin State Prison, less than an hour after his 76th birthday ended at midnight.

He received the first of three injections at 12:20 a.m. He then was given an extra dose of potassium chloride, the lethal chemical that stops the heart, at 12:35 a.m., and died minutes later, according to Corrections Department spokeswoman Elaine Jennings.

Allen - who was legally blind, nearly deaf and in a wheelchair - was the second-oldest put to death nationally since the Supreme Court allowed capital punishment to resume in 1976.

"Allen deserves capital punishment because he was already serving a life sentence for murder when he masterminded the murders of three innocent young people and conspired to attack the heart of our criminal justice system," state prosecutor Ward Campbell said.

His lawyers had raised two claims never before endorsed by the high court: that executing a frail old man would violate the U.S. Constitution's ban on cruel and unusual punishment, and that the 23 years he spent on death row were unconstitutionally cruel as well.

The high court rejected his requests for a stay of execution, about 10 hours before he was to be put to death.

On one of the orders, Justice Stephen Breyer filed a dissent, saying: "Petitioner is 76 years old, blind, suffers from diabetes and is confined to a wheelchair, and has been on death row for 23 years. I believe that in the circumstances he raises a significant question as to whether his execution would constitute cruel and unusual punishment. I would grant the application for stay."

The Supreme Court has never set an upper age limit for executions or created an exception for physical infirmity.

Gov. Arnold Schwarzenegger, the California Supreme Court and a federal appeals court previously refused to spare Allen's life.

Allen went to prison for having his teenage son's 17-year-old girlfriend murdered for fear she would tell police about a grocery-store burglary. While behind bars, he tried to have witnesses in the case wiped out, prosecutors said. He was sentenced to death in 1982 for hiring a hit man who killed a witness and two bystanders.

Allen's heart stopped in September, but doctors revived him and returned him to San Quentin Prison's death row.

"These infirmities are not simply the result of the passage of time or of old age, as some would suggest, but result from prison authorities' deliberate neglect of his medical needs while in the state's custody," said Annette Carnegie, one of Allen's attorneys.

Last month in Mississippi, John B. Nixon, 77, became the oldest person executed in the United States since capital punishment resumed. He did not pursue an appeal based on his age.