The execution of Donald Grant “was carried out with zero complications” at 10:16 a.m., state Attorney General John O’Connor said in a statement.
Grant’s lawyers appealed to the US Supreme Court for a stay, but Justice Brett Kavanaugh denied the application.
Grant was sentenced to death for the 2001 murders of Brenda McElyea and Felecia Suzette Smith, according to court documents filed to the Supreme Court by the Oklahoma attorney general.
“Justice is now served for Brenda McElyea, Felecia Suzette Smith, and the people of Oklahoma,” the attorney general said in a statement.
Postelle is scheduled to be executed on February 17.
In their initial petition to the court, lawyers for the two inmates had sought an injunction to stop Oklahoma from using lethal injection to administer the death penalty. Attorneys for the inmates had asked for the executions to be delayed pending a late February trial on the constitutionality of the lethal injection protocol.
Testimony submitted by the plaintiffs in court filings from a “board-certified anesthesiologist and a board-certified pain medicine specialist” alleged that execution by firing squad — not Oklahoma’s process of lethal injection — is appropriate because “firing squad will reliably cause a death that will be quick and virtually painless.”
CNN’s Paul Murphy and Ray Sanchez contributed to this report.