A convicted double murderer has been executed by firing squad, the first such execution in the United States since 2010, according to the South Carolina Department of Corrections.

"I want my closing statement to be one of love and a calling to my fellow Christians to help us end the death penalty," Brad Kieth Sigmon wrote ahead of his execution.

South Carolina executed a convicted murderer by firing squad on Friday, the first use of the method in the United States in 15 years.