Alfredo Prieto was executed in Virginia Thursday night for fatally shooting two George Washington University students outside Reston and killing a teenage girl in California nearly three decades ago.
Prieto, 49, was pronounced dead at 9:17 p.m.
He spoke last words before his execution -- the first and only time he spoke publicly regarding his crimes.
"I would like to say thanks to all my lawyers, all my supporters and all my family members. Get this over with," Prieto said, according to Virginia spokeswoman Lisa Kinney.
Federal Judge Clears Way for Execution of Alfredo Prieto
Clergy member Brent Epperson spoke with Prieto before he witnessed the execution.
"I asked if he had offered or asked for absolution for his sins or crimes," Epperson said. "He would not confirm or deny that, of course."
The U.S. Supreme Court refused to block the execution -- the first in Virginia in three years -- and a U.S. District Court in Richmond lifted a last-minute order blocking it.
Prieto, a native of El Salvador, was on death row in California for raping and murdering a 15-year-old girl when DNA evidence linked him to the rape and murder of Rachael Raver and the murder of her boyfriend, Warren Fulton III.
The victims were GW students when they were killed in 1988; their bodies were found in a field in Reston.
Prieto also was charged with raping and murdering 24-year-old Veronica Jefferson in Arlington in 1988. Prosecutors dismissed the indictment, saying seeking a fourth death sentence did not justify the expense. The convicted killer also was linked to the death of Manuel Sermeno, 27, who was found shot to death in a burning car in Prince William County in 1989.
Authorities have linked Prieto to several other killings, but he was never prosecuted for them because he already had been sentenced to death.
The Supreme Court refused on Thursday evening to stop the execution, and Judge Henry E. Hudson lifted a temporary order that blocked it. Prieto had requested to stay the execution because he claimed he was intellectually disabled.
A different federal judge had granted the temporary restraining order Wednesday after Prieto's attorneys raised concerns about a drug set to be used. Virginia officials say there were no problems with the drugs, which they obtained from Texas's prison system.
Hudson said Prieto's lawyers had not adequately shown that the drugs are unsafe.
Prieto's attorneys asked the court to delay the execution until Virginia officials disclosed more information about the supply of pentobarbital they received from Texas, saying they're concerned about the quality of the drugs and whether they would bring Prieto "gratuitous and unnecessary pain."
Virginia obtained pentobarbital from Texas to replace its supply of another sedative, midazolam, which expired Wednesday.
Prieto's lawyers asked for the name of the supplier, confirming its sterility and potency and they want documents showing that the drugs were properly handled. Texas allows prison officials to shield where they get execution drugs and Virginia officials did not provide that information.
Margaret O'Shea, a lawyer from Attorney General Mark Herring's office, urged the judge to dismiss the arguments, noting that Texas has used the same drugs without any problems in 24 executions over the past two years.
"It is time for this to end," she said, adding that Prieto murdered Raver and Fulton 27 years ago. "It is time for the carousel to end."