Oklahoma executed a man on Thursday for killing a co-worker in 1997, rejecting the recommendation of a state pardon board as it carried out the first in a series of 25 executions scheduled over the next 28 months.

James Coddington, 50, who admitted killing 73-year-old Albert Hale with a hammer, was executed by lethal injection at a state prison in McAlester, Okla.

Oklahoma resumed carrying out some executions in October 2021 after a pause of nearly seven years that followed a series of botched executions. But most of the state’s capital sentences remained on hold while a lawsuit over the use of a sedative in executions went to trial. When a judge upheld the use of the drug, Oklahoma scheduled 25 executions through December 2024, beginning with the one on Thursday.

Plans for Mr. Coddington’s execution were thrown into doubt for a time when the state’s Pardon and Parole Board recommended on Aug. 3 that his life be spared. An unusual coalition had formed over the past several weeks to oppose the execution, including a former director of the Oklahoma prison system and a Republican who once served as the speaker of the state’s House of Representatives. Both said that Mr. Coddington had rehabilitated himself and was far different from who he was when he committed the crime.

“It would not be in the best interests of the state of Oklahoma to execute someone who manifests such redemption,” the former director of the state’s prisons, Justin Jones, wrote in The Oklahoman newspaper this week.

But Gov. Kevin Stitt, a Republican, who appointed most of the board’s members, rejected their recommendation, and the execution was allowed to proceed.

Mitch Hale, a son of the victim, attended the execution and said that he did not believe that Mr. Coddington had ever been truly remorseful. He said Mr. Coddington had shown as much when, given an opportunity to say final words, he made no mention of the victim or the crime.

Instead, as Mr. Coddington lay on a gurney in the execution chamber, he thanked his relatives, friends and lawyers, according to reporters who witnessed the execution, and said, “Governor Stitt, I don’t blame you, and I forgive you.”

The execution was Oklahoma’s fifth since October. The state plans to execute four more prisoners this year, and then 10 each in 2023 and 2024.

Mr. Coddington said he was high on cocaine when he killed Mr. Hale, with whom he had worked at a car parts store for several years.

Mr. Coddington testified at his trial that he had gone to Mr. Hale’s home to ask for $50 to buy drugs, but that Mr. Hale had refused and had told him to seek help, sending Mr. Coddington into a rage. He said he grabbed a hammer and struck Mr. Hale in the back of the head, and then took money from the victim’s pants pocket.

Mitch Hale said after the execution that he had found no joy in watching it, but was glad it happened, because it would allow him and his family to move on after years of legal proceedings.

“This is finally over, and that’s the only thing we wanted, was just everything to stop,” Mr. Hale said at a news conference. “Unless you’ve been inside this system on the victim’s side, you don’t understand how you just get kicked around like a football. No one cares about us; it’s always the criminal’s side.”