Minute-by-minute account of America's first firing squad execution in 15 years

Warning: This story contains details of an execution, some of which readers may find distressing

Eyewitnesses have given a chilling account of what happened in the minutes leading up to America's first execution by firing squad in 15 years.

Brad Sigmon, 67, was executed on 7 March after being convicted of the 2001 murder of his ex-girlfriend's parents, David and Gladys Larke, in their South Carolina home before abducting his former partner with the intention of killing her as well.

Faced with the death penalty, Sigmon opted to be executed by firing squad, with the sentence being carried out just after 6pm local time.

Brad Sigmon was executed by firing squad on 7 March (South Carolina Department of Corrections)

Sigmon's mother and brother were not in attendance at the execution, neither was his former partner, however, multiple witnesses were allowed to attend the gruesome event and detailed a minute-by-minute account of how the sentence was carried out.

6:00pm

According to a report from MailOnline, Sigmon was brought into the death chamber at 6pm EST and looked over to the witness gallery before being strapped into the execution chair.

A white target was also placed over his heart.

6:02pm

Once Sigmon was strapped into the chair, which included head restraints and a basin to collect blood, his attorney read out the 67-year-old's final statement, which saw the newfound Christian speak out against the death penalty.

"I want my closing statement to be one of love and a calling to my fellow Christians to help us end the death penalty," the statement read.

Sigmon was the first man to be executed by firing squad in 15 years (Getty Stock Image)

"Nowhere does God in the New Testament give man the authority to kill another man."

6:03pm

According to numerous accounts from reporters in attendance, Sigmon mouthed the words 'I'm OK,' to relatives watching in the gallery before a hood was pulled over his head.

6:04pm

A blind was then lifted to reveal three volunteers from the South Carolina Department of Corrections who stood behind a wall which featured an opening at firing height. Each was armed with a rifle.

Recalling the final moments before the shots rang out, South Carolina TV journalist Anna Dobbins said: "We could not see the guns. There was no countdown or anything to tell us when the shots would be fired."

6:05pm

Each of the executioners fired simultaneously and were direct hits on target. Sigmon flinched and his chest rapidly rose and fell several times. Blood began to pool at his chest.

"It was very fast," Dobbins said of the killing.

He was found guilty of double murder after killing his ex-girlfriend's parents with a baseball bat (Legal team of Brad Sigmon)

Associated Press reporter Jeffrey Collins also provided an account of the event, detailing how the bullets - which are designed to break apart and cause maximum damage upon impact - meant the target placed over his heart 'disappeared instantly'.

"A jagged red spot about the size of a small fist appeared where Sigmon was shot. His chest moved two or three times. Outside of the rifle crack, there was no sound," he said.

6:06pm

A doctor entered the chamber and listened to Sigmon's heart for two minutes.

6:08pm

Chrysti Shain, of the South Carolina Department of Corrections, said Sigmon was pronounced dead.