An ex-soldier who raped and murdered a nurse he was convinced was a witch has been executed after 16 years on death row.

William LeCroy was put to death by lethal injection on Tuesday evening, the sixth federal execution since July after a lengthy hiatus in capital punishment at a national level.

The 50-year-old was pronounced dead at 9.06pm local time after officials with the US Bureau of Prisons administered him a fatal dose of the barbiturate pentobarbital.

The execution took place in Terre Haute, Indiana and came shortly after the US Supreme Court denied an 11th-hour petition.