LINCOLN, Neb. (AP) — Nebraska state officials are preparing for their first execution in two decades and their first-ever lethal injection with an untried combination of drugs that includes a powerful painkiller responsible for much of the nation's opioid epidemic and a paralyzing drug that could conceal whether something has gone wrong.

The execution planned for Aug. 14 at the Nebraska State Penitentiary in Lincoln comes with significant risks for Nebraska prison officials, who haven't carried out a death sentence since using the electric chair in 1997.

The Death Penalty Information Center says no state in modern history has resumed executions after such a long hiatus. Nebraska is also poised to become the first state to use a four-drug protocol, including three substances never before used in an execution.