Mass murderer Steven Ray Thacker was executed Tuesday night via lethal injection at the Oklahoma State Penitentiary, where he asked for forgiveness from his victims’ families.

“I would like to apologize sincerely to the families of Laci Hill, Forrest Boyd and Ray Patterson. I don’t deserve it, but as God has forgiven me, I hope you will forgive me for the pain I’ve caused,” Thacker said before being executed, as reported by the Tulsa World.

According to the newspaper, Thacker was administered lethal drugs at 6:03 p.m. Tuesday local time and was pronounced dead at 6:10 p.m.

Thacker, 42, was the fifth condemned inmate to be executed in the United States in 2013 and the first in Oklahoma, Reuters reported.

Thacker went on a three-state killing spree from December 23, 1999, to January 2, 2000, starting with the kidnapping, rape and murder of 25-year-old Laci Dawn Hill in Bixby, Okla.

Thacker entered his first victim’s home by claiming he wanted to buy the pool table she advertised for sale in a local paper. He then raped and murdered Hill, whose body was found in an abandoned cabin on Dec. 29, 1999, the World reported.

Thacker had been laid off as a plumber’s helper and was out of money, according to Reuters. He stole Hill’s credit card so he could buy Christmas presents for his family.

The Oklahoma man then went on the run and killed his next victim in Missouri.

Forrest Boyd, 24, was killed on New Year’s Day, 2000, after Thacker broke into his home. Thacker was startled by Boyd, who was returning to the house, when he stabbed the restaurant supervisor to death.

Thacker then stole Boyd’s car and drove to Tennessee, where the vehicle broke down. He got a tow to a service station in Dyersburg, Tenn., and stabbed service station owner Ray Patterson to death after the 52-year-old discovered the credit card Thacker used to pay for the tow was stolen.

Thacker received death sentences for the murders of Hill and Paterson. He received life without parole for pleading guilty to killing Boyd.

Nikki Hodgson, a friend of Hill’s, said Thacker’s execution brought “a little bit of closure,” but didn’t believe the punishment was just.

“It is so humane,” she said of lethal injection. Thacker is “just going to sleep. It’s nothing like what the victims endured.”

Hill’s best friend, Marnie Reed, said the execution didn’t bring her closure.

"When something like this happens ... you never truly move on. You just survive. It never leaves you, and this won't make it leave you,” she told the World.