Ricky Gray was executed in Virginia Wednesday for the 2006 murders of Bryan and Kathryn Harvey and their two daughters, 9-year-old Stella and 4-year-old Ruby.
The 39-year-old was pronounced dead at 9:42 p.m. at the Greensville Correctional Center, Lisa Kinney, spokeswoman for Virginia's Department of Correction said at a press conference.
Virginia last executed an inmate in 2015.
Gray's attorneys asked the US Supreme Court on Tuesday to stop his execution on the grounds that Virginia's never-before-used method of execution would violate Gray's constitutional rights. The justices denied the request before 7 p.m.
The request argued that Virginia planned to use an "experimental and unconstitutional method of execution" which includes midazolam — a controversial sedative at the center of several botched executions — and compounded potassium chloride.
"No state has ever used compounded midazolam in an execution, compounded potassium chloride in an execution, or two compounded drugs in the same execution," Gray's petition stated — statements that are true so far as is known from publicly available information. Many states' execution drug information is kept secret by law.
Virginia Governor Terry McAuliffe denied Gray's petition for clemency on Tuesday, saying he had "decided not to intervene in this case."
In a statement provided to BuzzFeed News, Gray's attorneys said that it was "disappointing that Governor McAuliffe has denied clemency for Ricky Gray."
The attorneys said that during the crimes, Gray was under the influence of a psychosis-inducing drug, PCP, which he had been addicted to since suffering "years of brutal sexual and physical abuse... at the hands of family members."
Their statement said that Gray was a "model prisoner" and that he was "filled with remorse for his victims."
"He has tried to honor the two Harvey girls by serving as a father figure to his much younger sisters and making sure their childhoods are better than what he endured," his lawyers said.
The US Court of Appeals for the 4th Circuit also denied a stay of execution for Gray on Friday.
Gray was sentenced to death for killing the well-known Harvey family at their Richmond home as they were preparing to host a New Year's Party in 2006. Gray and two accomplices had entered the home to rob the family, according to court documents.
The parents and their two young daughters were found dead after being bound, beaten, stabbed and cut in the neck in the basement of their home that was set on fire.
Gray described his actions in a signed confession, saying, "[I]t was a real nasty scene. How am I suppose[ d] to explain something like what happened? I started cutting their throats and they kept getting up and they [were] scaring me. I remember seeing the hammer and picking it up, and then...I was just hitting them all with the hammer. All I know is nobody was moving when I left out there."
After his arrest, Gray also confessed to killing his wife, court documents said. He also confessed to killing 21-year-old Ashley Baskerville — who was one of his accomplices during the Harvey slayings — as well as Ashely's mother Mary Baskerville-Tucker and stepfather Percyell Tucker, but he wasn't tried for those killings.
Kinney said Gray was asked if he had any last words and said, "Nope."