A twice-condemned serial killer who claimed he was intellectually disabled was executed in Virginia on Thursday after a series of last-minute appeals failed.

Alfredo Prieto was pronounced dead at 9:17 p.m. at the Greensville Correctional Center in Jarratt. The 49-year-old was injected with a lethal three-drug combination, including the sedative pentobarbital, which Virginia received from the Texas prison system.

Prieto, wearing glasses, jeans and a light blue shirt, did not resist and showed no emotion as he was strapped to the gurney.

"I would like to say thanks to all my lawyers, all my supporters and all my family members," he said, before mumbling, "Get this over with."

The El Salvador native was sentenced to death in Virginia in 2010 for the murder of a young couple more than two decades earlier. Rachael Raver and her boyfriend, Warren Fulton III, both 22, were found shot to death in a wooded area a few days after being seen at a Washington, D.C., nightspot.

Prieto was on death row in California at the time for raping and murdering a 15-year-old girl and was linked to the Virginia slayings through DNA evidence. California officials agreed to send him to Virginia on the rationale that it was more likely to carry out the execution.

He has been connected to as many as six other killings in California and Virginia, authorities have said, but he was never prosecuted because he had already been sentenced to death.