RICHMOND, Va. (AP) — Virginia Gov. Terry McAuliffe on Monday denied a last-minute attempt to delay the execution of a convicted serial killer who says that his life should be spared because he is intellectually disabled.

Unless the U.S. Supreme Court steps in this week, Alfredo Prieto will be the first Virginia inmate to be executed in nearly three years Thursday.

Prieto’s attorneys had asked the Democratic governor to grant a temporary reprieve of his execution so he could be transferred to California, where they hoped to argue that he’s ineligible for the death penalty because he is intellectually disabled.

But McAuliffe said Monday that he won’t intervene in the case, noting that state and federal appellate courts have already reviewed and denied the prisoner’s request for relief.

“It is the Governor’s responsibility to ensure that the laws of the Commonwealth are properly carried out unless circumstances merit a stay or commutation of the sentence,” McAuliffe said in a statement. “After extensive review and deliberation, I have found no such circumstances, and have thus decided that this execution will move forward.”

The El Salvador native was already facing execution in California for raping and murdering a 15-year-old girl when a Virginia jury sentenced him to death in 2010 for the 1988 killings of Rachael Raver and her boyfriend, Warren Fulton III. California officials agreed to send him to Virginia based on the rationale that Virginia was more likely to carry out the execution.

Authorities have said DNA and ballistics evidence have linked Prieto to several other killings in California and Virginia but he was never prosecuted because he had already been sentenced to death.

Rob Lee, one of Prieto’s attorney’s, called McAuliffe’s decision “profoundly disappointing.” He said in an email that it goes against past governors’ efforts “to ensure that every time the most severe and final sanction is carried out in Virginia, it is done fairly.”