Harding's execution was particularly noteworthy and controversial due to the fact that his death in the gas chamber took eleven minutes and was reportedly gruesome.

When Harding was a toddler, he was admitted to the Child Guidance Clinic in Little Rock, Arkansas, where a doctor treating him wrote in a report that his mother was "very immature and narcissistic" and unfit to care for her sons.

[4] The family stayed at the sanatorium for approximately two years before leaving, after which Harding moved repeatedly between living with his mother and his grandparents.

Harding witnessed Brown beating his mother; while he was in school, he struggled with behavioral issues, including defiance and truancy.

Soon after his release, Harding was convicted in federal court for "conspiracy to commit offense or defraud United States" and was imprisoned again for five years.

[12][13] On December 18, he robbed a man named Ronald Svetgoff and stole his car and identification cards, the latter of which he would use to feign his identity when he relocated to Arizona.

[12] Huth's murder was not immediately discovered, and weeks following the murder, authorities still had not found his body,[15] although by late January, a farmer had discovered Huth's body in a field near Paso Robles, California; he was found with his hands tied behind his back and a gunshot wound in his head.

[17] Later, while still in San Diego, Harding robbed four people in an optometrist's office and ordered one of the robbery victims to drive him to an unknown woman's house.

[15] On January 24, 1980, Harding fled to Phoenix, Arizona, where he gained entry to a hotel room belonging to 38-year-old gastroenterologist Allen F. Gage.

[12][11] On January 25, 1980, Donald Harding posed as a security guard to gain entry into a motel room in Tucson, Arizona, where Robert A.

Once both men were critically injured, Harding stole Wise's briefcase, which contained his credit cards; he then took Concannon's Oldsmobile.

Wise's body was on the floor next to the bed, tied to the bedpost by a restraint wrapped around his neck with his hands and ankles bound together.

[11] After the encounter with Robert Wise's wife, Harding drove the stolen car to a reserved parking lot on the campus of Northern Arizona University in Flagstaff.

While Harding drove away from the parking lot, the dispatcher returned with information about the car having been stolen and possibly involved in two homicides.

The campus police officer then followed Harding, arrested him, and searched him, finding a .25 caliber pistol in one of his pockets, an identification card reading "Security Guard," another identification card reading "Special Officer," a Texas driver's license issued to a man named Ronald Gene Svetgoff, and an Oklahoma driver's license issued to the same man.

[1] At the time of his capture, the FBI office in Flagstaff announced Harding was wanted for investigation in connection with a total of five murders, six kidnappings, 12 armed robberies, and four carjackings across Arizona, California, Nevada, Oklahoma, Utah, Tennessee, and Texas.

Harding was subsequently charged with the murders of Robert Wise and Martin Concannon, and he was booked into the jail in Coconino County, Arizona.

The board ultimately refused to recommend that then-Governor Fife Symington grant mercy in the form of a reprieve or commutation to life imprisonment.

[20] Prior to Harding's execution, around 150 people staged an anti-death penalty protest outside of the Florence State Prison walls.

Martin Concannon's widow elected not to view the execution,[22] but Warden Roger Crist, then-Attorney General Grant Woods, Harding's religious advisor, and six reporters were witnesses.

[4] Harding ate a last meal consisting of fried eggs, several strips of bacon, toast with butter and honey, and orange juice.

Reporters claimed Harding also made obscene gestures with his middle finger towards Attorney General Woods as the gas spread in the chamber.

Arizona State Representative Lela Steffey had proposed the change from the gas chamber earlier in 1992 due to concerns about air pollution involved in venting lethal gas after an execution, and Steffey stated polls showed a majority of Arizonans supported the switch to lethal injection; however, the movement did not gain momentum until after Harding's execution.

[26] During the 1992 election, a referendum allowed Arizonans to vote on whether or not the state should adopt lethal injection; voters approved the change in execution method.

The New York Times and Newsweek claimed Attorney General Woods became ill and vomited at the sight of Harding's convulsions.