South Carolina is planning to execute a prisoner on Friday evening with a firing squad, an extremely rare method that has not been used in the United States since 2010.

The inmate, Brad Sigmon, 67, was convicted of killing his ex-girlfriend’s parents, David and Gladys Larke, with a baseball bat in 2001.

A judge ordered Mr. Sigmon to choose from three methods of execution: lethal injection, electrocution or firing squad. His lawyer, Gerald King, said that Mr. Sigmon chose to be shot because he had concerns about South Carolina’s lethal injection process.

If the execution is carried out, Mr. Sigmon will be the first inmate killed in such a manner in the state’s history. Polls show that a majority of Americans favor the death penalty, but many view the firing squad as an archaic form of justice. But as lethal injection drugs have become harder to obtain — and have at times resulted in botched executions — several states have recently legalized firing squads as an execution method.

Utah is the only state that has used a firing squad in modern times; in addition to 2010, it did so in 1996 and 1977.

Mr. Sigmon is to be executed in the death chamber at the Broad River Correctional Institution in Columbia, S.C., the state capital, shortly after 6 p.m.