FLORENCE, Ariz. -- Convicted killer Donald Eugene Harding, 43, was executed in the gas chamber a few minutes after midnight Monday, becoming the first person to be executed in Arizona in 29 years.
Outside the prison about 150 persons held a candle-light vigil to protest the death penalty.
Late Sunday the state Board of Pardons and Parole rejected an eleventh-hour appeal to spare the life of the condemned.
Following a marathon hearing involving testimony from 22 people, most of them death penalty opponents, the seven-member board voted unanimously to let death sentence stand.
Among those pleading for a stay of execution were Harding's brother, Darryl, and representatives of the Catholic, Methodist and Episcopalian churches.
Representatives of the state attorney general represented the opposite end of the spectrum, urging the Board to allow the 43-year-old Harding to keep his appointment with the gas chamber.
Harding was convicted for killing three men during a 1980 crime spree.
The final legal obstacle was an appeal to the U.S. Supreme Court filed by the Arizona state attorney general's office. Prosecutors challenged a stay of execution issued Thursday night by the 9th Circuit Court of Appeals.
Included among some 10 motions for a stay was newly discovered medical evidence on 'organic brain syndrome,' involving possible physical damage to some part of the brain at birth, causing impulsive behavior.
The Supreme Court lifted the stay of execution Saturday, clearing the way for Monday's execution.
Arizona law required that Harding's case face a final hearing before the Arizona State Board of Pardons and Parole. The board began a clemency hearing Sunday at 9 a.m. which lasted more than 11 hours.
Sparing Harding's life required the state board recommending clemency to Gov. Fife Symington, who only then has the authority to suspend Harding's appointment with the executioner.
The last time Arizona used its gas chamber was March 14, 1963, when convicted murderer Manuel Silvas was put to death.
Currently there are 100 inmates -- 99 men and one woman -- officially on Arizona's Death Row, although four are housed in other states.
Harding is not the longest-serving condemned inmate. Others have resided on Death Row since 1976. He just happens to be the first to have exhausted virtually all avenues of appeal.
'It's just the way his legal ball bounced through the system,' said Mike Arra, spokesman for the Arizona Department of Corrections.
On the night of Jan. 24, 1980, Harding, posing as a security guard, entered the Phoenix motel room of Allen Gage, bound the victim's hands and feet with duct tape and stuffed a gag in his mouth.
Harding took Gage's wallet, stole his car and drove to Tucson, leaving Gage to die of asphyxiation, face down on the floor.
On the following day, Harding used the same ruse to rob and kill two men in a Tucson motel, tying them up and gagging them, but also shooting both in the back of the head at close range. Killed were Robert Wise and Martin Concannon.
Harding left Gage's car at the Tucson crime scene. Later that evening, before the bodies were discovered, Harding appeared at Wise's home in Mesa, knocking on the door and asking Wise's wife whether Robert Wise was home. Prosecutors speculate Harding then left because Mrs. Wise had a large dog with her.
He was arrested in Flagstaff Jan. 26, 1980, in possession of Gage's wallet and identification and driving Concannon's car.
Officials at the Arizona State Penitentiary in Florence said they were well-prepared for the execution.
'The gas chamber has been something that has been steadily maintained over the years by the administration of the state prison at Florence,' Arra said. 'As this so-called first execution in almost 30 years has been getting closer, we have been rehearsing, testing, planning, writing procedures.
The job is performed by pulling a lever that drops cyanide pellets into a solution of sulfuric acid in distilled water, located in a small vat directly below the prisoner's chair, creating a killer dose of cyanide gas.
Under Arizona law, which has not been changed for decades, lethal gas is the only form of capital punishment. A bill in the current session of the Legislature would make lethal injection the preferred method, but even if passed the change would require voter approval in November before becoming law.