HOUSTON (AP) — South Carolina is preparing this week to execute a man by firing squad, a capital punishment method that hasn’t been used in the U.S. in nearly 15 years.

Since the Supreme Court lifted its ban on capital punishment in 1976, states have used five different execution methods: lethal injection, electrocution, lethal gas, firing squad and hanging.

Brad Sigmon is scheduled to die Friday in South Carolina. He was convicted of killing his ex-girlfriend’s parents with a baseball bat at their home in 2001.

Here’s a look at how the U.S. executes people:

Most US executions are by lethal injection

Lethal injection has been the preferred method in the modern era, with 1,428 carried out since 1976. Texas has done the most, killing 593 inmates, according to the Death Penalty Information Center, a Washington, D.C.-based nonprofit center.

Twenty-eight states as well as the U.S. military and U.S. government authorize the use of lethal injection, in which an inmate has a deadly mixture of drugs injected into them as they are strapped to a gurney.

But throughout its use, lethal injection has been plagued by problems, including delays in finding suitable veins, needles becoming clogged or disengaged and problems with securing enough of the required drugs.

“A number of states are beginning to experiment with new methods of execution … because of the problems with lethal injection,” said John Banzhaf, a professor emeritus of law at George Washington University Law School.

Use of electrocution is down since 2000

Nine states authorize the use of electrocution, including Alabama, Arkansas, Florida, Kentucky, Louisiana, Mississippi, Oklahoma, South Carolina and Tennessee. Since 1976, 163 electrocutions have been carried out. But only 19 have been done since 2000.

In this method, a person is strapped to a chair and has electrodes placed on their head and leg before a jolt of between 500 and 2,000 volts runs through their body. The last electrocution took place in 2020 in Tennessee.

Texas used electrocution from 1924 to 1964, killing 361 inmates, according to the state’s Department of Criminal Justice. The electric chair Texas used was nicknamed “Old Sparky.” It is now displayed at the Texas Prison Museum in Huntsville, where the state’s death chamber is located.

Alabama resumes the use of lethal gas

Lethal gas is authorized as the default execution method in eight states: Alabama, Arizona, California, Louisiana, Mississippi, Missouri, Oklahoma and Wyoming.

From 1979 to 1999, 11 inmates were executed using this method, in which a prisoner would be strapped to a chair in an airtight chamber before it was filled with cyanide gas.

In 2024, Alabama revived this method when it became the first state to use nitrogen gas to execute Kenneth Eugene Smith. A mask is placed over a prisoner’s face and nitrogen gas is pumped in, depriving the person of oxygen and resulting in death.

Alabama’s last such execution took place in February.

Firing squads are rarely used in the modern era

Since 1977, only three inmates have been executed by firing squad and all were in Utah, with the last one in 2010, according to the Death Penalty Information Center.

Five states including Idaho, Mississippi, Oklahoma, South Carolina and Utah authorize its use, but it is not the primary execution method. For this method, an inmate is usually bound to a chair and is shot through the heart by a group of prison staffers standing 20 to 25 feet (6 to 7.6 meters) away.

Idaho has had firing squad executions on the books as a backup if lethal injection drugs are unavailable since 2023. But in the wake of last year’s botched lethal injection attempt on Thomas Eugene Creech, lawmakers are considering a bill to make firing squads the primary execution method.

The bill’s sponsor, Republican Sen. Doug Ricks, has suggested Idaho could use a firing squad machine, triggering the guns electronically to eliminate the need for additional execution team members.

Hanging was once the primary execution method

In the U.S., hanging was the main method of execution until about the 1890s, according to the Death Penalty Information Center.

Data collected by researchers of U.S. executions from 1608 to 2002 found 9,322 people were put to death by hanging, in which a person was blindfolded and their hands and legs were secured before a noose was placed around the neck and they fell through a trap door.

But in capital punishment’s modern era, only three individuals in the U.S. have been executed by hanging in 1993, 1994 and 1996. New Hampshire’s remaining death row inmate could be executed by hanging if lethal injection is not available.

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Associated Press video journalist Cody Jackson in Fort Pierce, Florida, and writer Rebecca Boone in Boise, Idaho, contributed to this report.

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Follow Juan A. Lozano on X at juanlozano70.