WASHINGTON, United States (AFP) — A South Carolina man convicted of murdering his ex-girlfriend’s parents was put to death by firing squad on Friday in the first such execution in the United States in 15 years, prison officials said.

Brad Sigmon, 67, who confessed to murdering David and Gladys Larke in 2001 with a baseball bat, was executed by a three-person firing squad at the Broad River Correctional Institution in the state capital Columbia, prison spokeswoman Chrysti Shain said.

Sigmon had asked the Supreme Court for a last-minute stay of execution but it was denied.

South Carolina Governor Henry McMaster also rejected his appeal for clemency.

Sigmon had a choice between lethal injection, the firing squad or the electric chair as his manner of execution.

Gerald “Bo” King, one of his lawyers, said Sigmon had chosen the firing squad after being placed in an “impossible” position, forced to make an “abjectly cruel” decision about how he would die.

“Unless he elected lethal injection or the firing squad, he would die in South Carolina’s ancient electric chair, which would burn and cook him alive,” King said.

“But the alternative is just as monstrous,” he said. “If he chose lethal injection, he risked the prolonged death suffered by all three of the men South Carolina has executed since September.”

The last firing squad execution in the United States was in Utah in 2010. Two others have also been carried out by firing squad in the western state — in 1996 and in 1977.

The 1977 execution of convicted murderer Gary Gilmore was the basis for the 1979 book “The Executioner’s Song” by Norman Mailer.

The vast majority of US executions have been done by lethal injection since the Supreme Court reinstated the death penalty in 1976.

Alabama has carried out four executions recently using nitrogen gas, which has been denounced by UN experts as cruel and inhumane. The execution is performed by pumping nitrogen gas into a facemask, causing the prisoner to suffocate.

Three other states — Idaho, Mississippi and Oklahoma — have joined South Carolina and Utah in authorizing the use of firing squads.

There have been six executions in the United States this year, following 25 last year.

The death penalty has been abolished in 23 of the 50 US states, while three others — California, Oregon and Pennsylvania — have moratoriums in place.

Arizona, Ohio and Tennessee had paused executions but recently announced plans to resume them.

President Donald Trump is a proponent of capital punishment and on his first day in office called for an expansion of its use “for the vilest crimes.”