If Sigmon's execution moves forward, he will become the first inmate in South Carolina executed by firing squad in modern history and the fourth in the U.S. since 1977.

South Carolina plans to execute its first prisoner by firing squad on March 7 inside the same death chamber it's used for dozens of other executions. Firearms experts say that could be risky.

The inmate was 67-year-old Brad Sigmon, who was convicted of double-murder. The last execution by firing squad in the U.S. was in Utah in 2010.