Just six months earlier, Gary Gilmore had robbed and murdered a petrol station worker, then a hotel manager the next day.

Though both victims had cooperated with the robberies, he killed them anyway.

Gary Gilmore was executed by firing squad. (Nine Archives)

When he tried to throw away the gun used in both murders, it went off and shot him in the hand.

Gilmore was found soon afterwards.

The October trial took two days and the jury only needed a few hours to deliberate.

Gilmore was unusual in that he actively opposed efforts to spare his life.

Gilmore said he wanted anti-death penalty activists to “butt out”.

When his mother tried to sue for a stay of execution, he fought to stop her lawsuit.

“This is my life and this is my death. It’s been sanctioned by the courts that I die and I accept that,” he said.

Gary Gilmore was the first person executed after the death penalty was reinstated. (Nine Archives)

His last words were: “Let’s do it.”

Under Utah law, one person in the five-member firing squad would unknowingly be firing a blank.

This way, no-one would know for sure if they had killed the prisoner.

But when his brother looked at his body, he found there were five bullet holes in his shirt.

In a particularly macabre sketch, the comedy show Saturday Night Live sang a song called “Let’s Kill Gary Gilmore for Christmas” several days before his death.

Cast on Saturday Night Live performed a song called “Let’s Kill Gary Gilmore for Christmas” several days before his death. (NBC)

Five years earlier, the United States Supreme Court had placed a moratorium on the death penalty.

The Supreme Court made the decision after an “emotionally disturbed and mentally impaired” man was sentenced to death after a one-day trial in 1968.

As a result of the moratorium, more than 600 prisoners on death row had their sentences commuted to life imprisonment.

Among those spared were Robert F Kennedy’s assassin, Sirhan Sirhan, and the murderers in the Manson family.

The death penalty was reinstated after US states amended their laws to be more specific.

Charles Manson followers Susan Atkins, Patricia Krenwinkel and Leslie Van Houten had their death sentences commuted in 1972. (AP/AAP)