A divided Oklahoma panel declined on Wednesday to recommend clemency for Richard Glossip, a death row prisoner whose case has been taken on by a diverse range of supporters, including state lawmakers, Kim Kardashian and the Republican state attorney general, who argued that it would be “a grave injustice” to put him to death.
Mr. Glossip, 60, was convicted of arranging the 1997 murder of Barry Van Treese, who owned a motel in Oklahoma City where Mr. Glossip worked as manager. But Mr. Glossip’s lawyers and supporters have argued that the motel handyman who carried out the killing, Justin Sneed, had acted alone.
State lawmakers on both sides of the aisle have said Mr. Glossip should be spared, with one Republican death penalty supporter saying he would vote to outlaw executions in the state if Mr. Glossip was put to death.
Gentner Drummond, the state attorney general, told the Oklahoma Pardon and Parole Board that though he believed Mr. Glossip most likely arranged the murder, the evidence was not strong enough to warrant a conviction, let alone a death sentence.
“I believe it would be a grave injustice to allow the execution of a man whose trial was plagued by many errors,” Mr. Drummond said. He said he was not aware of any previous attorney general in the state ever supporting a reprieve for a death row prisoner.
The Parole Board was split 2-2 on whether to recommend clemency, with a fifth member recusing himself, meaning that Mr. Glossip’s execution — scheduled for May 18 — can proceed.
Family members of Mr. Van Treese said at the hearing that they felt that the process had been one-sided, with a niece, Carrie Jarboe, saying that Mr. Glossip was a “habitual liar” who had managed to attract attention from high-profile supporters. Earlier this week, Ms. Kardashian asked her 75 million Twitter followers to call the Pardon Board and urge its members to spare Mr. Glossip.
The Van Treese family said they did not want an innocent man to be executed but felt Mr. Glossip was responsible for the killing.
In a statement after the vote, a lawyer for Mr. Glossip, Don Knight, said his legal team would continue to seek a reprieve in court and called on Gov. Kevin Stitt, a Republican, to reverse the death sentence.
“The execution of an innocent man would be an irreversible injustice,” Mr. Knight said, adding: “If the jury had known what we know now, they never would have convicted Mr. Glossip.”
Mr. Stitt had twice delayed Mr. Glossip’s execution while a court evaluated his appeals. A spokesman for the governor did not immediately respond to questions on Wednesday about whether he would intervene.
At trial, Mr. Sneed testified that Mr. Glossip had directed him to kill the victim and had promised to pay him thousands of dollars. That was the backbone of the case, but a pair of recent investigations cast doubt on the claim.
Mr. Glossip’s advocates say that Mr. Sneed had acted alone in killing Mr. Van Treese and had done so in order to rob him of money that Mr. Sneed and his girlfriend planned to use to buy drugs. That version of the crime comes in part from interviews with inmates who were in jail with Mr. Sneed on unrelated charges and to whom he confided about the crime. Those accounts were not heard by the jurors who convicted Mr. Glossip and sentenced him to death.
Mr. Sneed ultimately took a plea deal of life in prison and testified against Mr. Glossip, avoiding a trial and possible death sentence.
Oklahoma has executed 13 people over the last two years, tied with Texas for the most of any state. Oklahoma also has a troubled history of botched lethal injections and, in 2015, temporarily halted executions for several years after a series of problematic executions, including one in which executioners mistakenly allowed a man to regain consciousness.
Oklahoma’s lethal injection procedure was challenged in court, but the state prevailed and has since scheduled a series of executions, saying at one point that it hoped to execute 25 prisoners before 2025. After Mr. Glossip’s scheduled execution, three more are scheduled for this year so far.