COLUMBIA, S.C. (AP) — When a South Carolina man who killed his ex-girlfriend’s parents with a baseball bat steps into the death row chamber Friday night, it won’t be lethal injection or electrocution that ends his life.

It will be three people holding rifles about 15 feet (4.6 meters) away who will complete his punishment in what will be the United States’ first firing squad execution in 15 years.

Some 46 prisoners have been executed by lethal injection and electrocution in South Carolina since 1985. Brad Sigmon’s execution will be the first by firing squad. Just three inmates — in Utah in 1977, 1996 and 2010 — have faced a firing squad in the U.S. since the death penalty was reinstated in 1976.

Reporters, family members of Sigmon’s victims and his lawyer will view the execution inside the same building used for all executions over the past 35 years, although prison officials say the glass separating the witness room from the death chamber is now bulletproof. Sigmon can give a last statement if he wishes.

The crime

Sigmon, 67, is being executed for the 2001 baseball bat killings of his ex-girlfriend’s parents at their home in Greenville County. They were in separate rooms, and Sigmon went back and forth as he beat them to death, investigators said.

He then kidnapped his ex-girlfriend at gunpoint, but she escaped from his car. He shot at her as she ran but missed, according to prosecutors.

In a confession, Sigmon said, “I couldn’t have her. I wasn’t going to let anybody else have her.”

How Friday’s execution will unfold

Death row inmates in South Carolina are housed in a building adjacent to the death chamber at the Broad River Correctional Institution in Columbia. Shortly before his execution, Sigmon will be moved to an individual cell closer to where his life will end.

Just before 6 p.m., the warden will ask Gov. Henry McMaster by phone if he is granting clemency and the Attorney General’s Office if there any any legal blocks to the execution. If both answers are no, Sigmon will enter the death chamber and the witness room curtain will be opened.

Sigmon can give a last statement. Then he will be strapped to a metal chair that sits on top of a catch basin. The right side of Sigmon’s face and body will be toward the witnesses. A hood will be placed on his head. A medical professional will briefly examine him to place a target over his heart, according to state protocols released in 2022.

Fifteen feet (4.6 meters) away will be three state Corrections Department volunteers with rifles. All three will have live ammunition. They will fire from an opening in a wall the witnesses can’t see.

A doctor will come out, passing by the state’s immobile electric chair, to confirm Sigmon is dead. The witnesses will leave after signing an official document that they witnessed the execution.

When lethal injections take place, a gurney is in the death chamber and behind it is a curtain that blocks the view of the electric chair and the firing squad chair.

The firing squad

Not much is known about the people who will fire the rifles. Prison officials said they have “completed all required training.”

A shield law passed in 2023 in part to keep the name of any supplier of lethal injection drugs secret also keeps secret many other details about the firing squad, from what training it received to the names of anyone on the execution team.

A few details came out in court in 2022 during an unrelated trial that ultimately led the state Supreme Court to rule the firing squad, electric chair and lethal injection were all legal and didn’t violate the U.S. Constitution’s ban on cruel and unusual punishment.

The state will use .308-caliber Winchester 110-grain TAP Urban ammunition often found in police rifles, said Colie Rushton, the director of Security and Emergency Operations at the Corrections Department.

Why that bullet?

The round is designed to break apart as soon as it hits something firm, in this case the prisoner’s rib cage. Fragments will spread out and the intent is to destroy as much of the heart as possible.

A medical expert for the state said at the 2022 trial that if the heart is heavily damaged an inmate would lose consciousness almost immediately and likely would not feel pain. The doctor said survivors of gunshots often report first feeling like they were punched and pain only following a few seconds later.

But a doctor testifying for inmates said it would likely take longer for an inmate to lose consciousness and that as anyone who has ever broken a rib knows, breathing becomes extremely painful once the bones in the chest are cracked.

If the aim of the executioners is not true, death could take even longer. Damaged hearts can continue to pump blood.

The information released by the state to the public gives no indication what might happen if an inmate survives the initial shots. At the 2022 trial, witnesses indicated the squad could fire again.