WASHINGTON (AFP) - The state of Virginia late on Thursday (Oct 1) executed multiple murderer Alfredo Prieto, rejecting last-minute court appeals from lawyers for the Salvadoran immigrant.
Prison officials said in a statement that Prieto, who was put to death by lethal injection, was pronounced dead at 9.17pm.
His final words, they said, were: "Let's get this over with."
Prieto had been convicted of or linked to nine killings across the United States.
His attorneys had filed a lawsuit seeking to temporarily postpone the execution over objections to the mix of drugs used in the lethal injection, but a federal judge rejected their appeal.
Prieto's main attorney Robert Lee complained that he had filed an 11th-hour appeal on behalf of his client with the US Supreme Court, but that the execution was carried out before the US highest court could render a decision.
"The Justices of the Supreme Court of the United States were considering Mr Prieto's request for a stay of execution but the Virginia Department of Corrections went ahead with the execution without waiting for a decision from the Justices," Mr Lee said in a statement.
Crimes that Prieto has been convicted or linked to by evidence include the 1988 shootings of Ms Rachael Raver and Mr Warren Fulton III on the outskirts of the US capital, the Washington Post reported.
The authorities say they believe he also raped four of his victims, including a 15-year-old girl in California, where he was arrested in 1990, according to the newspaper.
According to Mr Lee, Virginia "executed a man without knowing whether he has intellectual disability or not, using drugs that are far beyond their approved date of use".
Prieto's execution was the third scheduled in the United States this week, just two of which were actually carried out.
A Georgia woman was put to death on Tuesday. Oklahoma's governor on Wednesday, however, postponed the execution of a convicted murderer for more than a month while officials address concerns about the drugs to be used in the execution.
The United States remains the only Western country to maintain the death penalty and has carried out 21 executions so far this year.
Prieto's execution had been temporarily put on hold by a US District Court judge in Alexandria, Virginia, after his lawyers challenged the planned use of one of three drugs to be included in the lethal injection.
The case moved to Richmond, the capital of Virginia, where US District Court Judge Henry Hudson lifted the hold in the early afternoon.
"The state and the victims of crime can expect the moral judgment of the state to be carried out without delay," Judge Hudson wrote in the opinion issued hours later.
"This is not an instance where there are any questions as to innocence or sufficiency of due process of an individual set to be executed," he added.
US states using the death penalty have faced obstacles over shortages of lethal injection drugs after European suppliers stopped supplying pentobarbital for use in executions.
The shortages have prompted prison departments in the states that still allow the death penalty to seek new supply sources or new drug mixes.