Reporter describes disturbing reality of witnessing rare execution method recently used for first time in 15 years

Warning: This article contains graphic descriptions of violence which some readers may find distressing.

A reporter who witnessed the first firing squad execution carried out in the US in 15 years described the disturbing and horrific nature of the method of carrying out a death sentence.

Convicted murderer Brad Sigmon was executed by earlier this year, having requested a firing squad as his method of death instead of a lethal injection or the electric chair.

Before Sigmon's execution, the last US prisoner to be put to death by firing squad was convicted killer Ronnie Lee Gardner, who was executed in 2010 and said he chose the firing squad as it was 'so much easier' and there would be 'no mistakes'.

Execution by firing squad is only legal in a handful of US states and before Sigmon's death sentence was carried out there had only been four instances of it being used in the US since 1960, all in Utah.

A month after Sigmon's execution, another death row inmate named Mikal Mahdi was put to death via firing squad.

Brad Sigmon was executed by firing squad, having requested it as the way his death penalty would be carried out (South Carolina Department of Corrections)

Associated Press reporter Jeffrey Collins said after Sigmon's execution that he had seen 10 previous death sentences carried out in South Carolina but that 'none of the previous 10 prepared me' for witnessing the firing squad.

He explained that in his time as a reporter he'd witnessed nine lethal injections and one person put to death by the electric chair, but that Sigmon was the first firing squad execution he'd seen.

While he did as much research as he could to prepare for what he was about to witness, Collins said he couldn't really know what to expect when he'd 'never seen someone shot at close range'.

The reporter described it as a 'faster' and 'more violent' method of execution than a lethal injection, adding that it was 'a lot more tense' as well.

He described how it was 'about two minutes' after prison officials put the hood over Sigmon's head when the firing squad pulled their triggers.

The prison room where death row inmate Brad Sigmon was executed by firing squad (South Carolina Department of Corrections)

"There was no warning or countdown. The abrupt crack of the rifles startled me," Collins wrote of his experience witnessing the reality of a firing squad.

"And the white target with the red bullseye that had been on his chest, standing out against his black prison jumpsuit, disappeared instantly as Sigmon’s whole body flinched."

Collins recounted that 'a jagged red spot about the size of a small fist appeared where Sigmon was shot', and that the man's 'chest moved two or three times'.

Less than a minute later a doctor stepped out to examine Sigmon, and a minute after that the man was declared dead.

The reporter said he remembered the 'thunk of the breaker' when he witnessed an execution by electric chair in 2004, saying he'd remember 'the crack of the rifles' and 'that target disappearing' just as much.