Andrew Cook apologized to his family and the families of the two people he murdered 18 years ago, but he didn’t ask for their forgiveness.

“I’m not going to ask you to forgive me,” Cook said a few moments before he was executed by lethal injection late Thursday for killing two Mercer University students on Jan. 2, 1995. “I can’t even do it myself.”

He said it was senseless to kill Grant Patrick Hendrickson and Michele Cartagena. Cook, then 20 years old, picked the couple at random when he came up on them parked at “the Point,” a small peninsula that juts into Lake Juliette. He fired 14 shots from an AR-15 and another five from a 9 mm Ruger at them and then dragged Cartagena about 40 feet from the car, partially undressed her, knelt between her legs and spit tobacco juice on her in an attempt to make it look like a robbery and sex crime, prosecutors said.

He thanked his family for “their support, for being with me, and I’m sorry I took so much from you all.”

At 11:22 p.m. Thursday, the 38-year-old Cook became the first person to be executed in Georgia using only one drug, a massive dose of pentobarbital. The state abandoned the three-drug combination it had used on 29 other men because two of the drugs were becoming impossible to secure.

His death came almost 5 1/2 hours after his final appeal was filed with the U.S. Supreme Court just before 6 p.m. He had been scheduled to die at 7 p.m. Thursday, but the state put his lethal injection on hold until the Supreme Court denied his appeal just before 11 p.m.

His lawyers asked for mercy by claiming Cook had changed during his time in prison and was a good man, that he had become spiritual while on death row and he wanted to help the families of his victims.

Hendrickson’s mother, Mary, told a Macon television station that the 18-year wait has been hard.

“I think that’s what it was: the devil’s work,” she told WMAZ-TV. “When all that is going on, I was just thinking to myself: ‘Well, the devil is not going to win. He’s not going to win over my heart. He is not going to win.’”

Two days earlier, Warren Hill won a stay of his execution set for Tuesday evening with a claim that that he had new evidence proving beyond a reasonable doubt that he is mentally ill. Hill was serving a life sentence in 1990 for killing his 18-year-old girlfriend four years earlier when he beat to death his cellmate, Joseph Handspike, with a nail-studded board, saying “you ain’t bad now.”

In Cook’s case, it was harder to connect him to his victims than it was to connect Hill to Handspike because Cook had no connection to Hendrickson or Cartagena. Investigators had a report of a Honda CRX seen driving off. They knew the types of weapons used. And they had recovered DNA in the tobacco juice spit on Cartagena’s leg.

Investigators contacted Cook two years after the crime as they were seeking DNA samples from area people who owned weapons like those used to kill Hendrickson and Cartagena.

To get a reluctant Cook to cooperate, an investigator asked Cook’s father, then an FBI agent, for help. Andrew Cook confessed to his father, and then John Cook relayed the details to investigators. The father also testified at his son’s trial.

According to pleadings filed in the final days before the execution, John Cook “did what he thought was right” and he never expected his son to get the death penalty.

But instead of Cook “harboring bitterness toward his father,” his attorneys wrote, “Andy has embraced him … Andy has never wavered in his support for his father.”