Oklahoma State Penitentiary death row inmate Richard Glossip seen on January 19, 2021.
CNN  — 

Oklahoma’s governor on Tuesday ordered that the scheduled September execution of death row inmate Richard Glossip be delayed until December – a move that Glossip’s attorneys, who argue he’s innocent, say will allow an appellate court to consider a new hearing.

This is the fourth time Glossip has received a stay of execution or a reprieve, his attorneys say, since he was convicted of murder in the 1997 death of his boss.

Gov. Kevin Stitt’s order is a 60-day stay of execution that starts September 22, which, until Tuesday, was Glossip’s most recent execution date. The order reschedules the execution for December 8, more than two weeks after the stay expires.

The stay is “granted to allow time the Oklahoma Court of Criminal Appeals to address a pending legal proceeding,” the order reads.

Glossip’s attorneys say that refers to the court’s review of Glossip’s petition for a new evidentiary hearing in the case – a request that followed an independent June report that his attorneys say further points to Glossip’s innocence. Glossip also filed a clemency petition with the Oklahoma Pardon and Parole Board this month.

“We are extremely grateful for Gov. Stitt’s thoughtful and compassionate decision to grant a 60-day reprieve for Rich’s execution date,” Glossip’s attorney Don Knight said in news release Tuesday.

Glossip, a motel manager, was convicted of capital murder in the 1997 death of his boss, Barry Van Treese, on prosecutors’ theory that he ordered the killing.

Prosecutors acknowledged that a different employee, then-19-year-old maintenance worker Justin Sneed, killed Van Treese with a baseball bat in Oklahoma City, but told jurors Sneed did so in a scheme masterminded by Glossip. Glossip maintained he had nothing to do with it.

Sneed received a life sentence in a plea deal for his testimony against Glossip.

Glossip initially was convicted and sentenced to death in 1998, but that was overturned in 2001 because of ineffective defense counsel. Glossip was convicted in a second trial in 2004 and again sentenced to death. In an interview with CNN in 2015, Glossip said he believed Sneed implicated him to avoid the death penalty.

In 2015, anti-death penalty activists rallied outside the US Supreme Court in a final attempt to prevent Glossip's execution.

In February, citing years of concerns about the conviction, some Oklahoma state lawmakers asked the law firm Reed Smith to investigate the Glossip case, in which the firm had no prior involvement.

The firm released a report in June that said a “sloppy and truncated” police investigation and destroyed evidence resulted in Glossip’s conviction. It concluded “the 2004 trial cannot be relied on to support a murder-for-hire-conviction. Nor can it provide a basis for the government to take the life of Richard E. Glossip.”

“Our conclusion is that no reasonable jury, hearing the complete record and the uncovered facts detailed in this report, would have convicted Richard Glossip of capital murder,” Reed Smith attorney Stan Perry said in June.

Glossip has been on the verge of execution three times before, even being served three separate last meals, according to his attorney. In September 2015, Glossip was minutes from execution when then-Gov. Mary Fallin postponed it over concerns the state procured an unauthorized drug for the procedure.

CNN’s Rebekah Riess, Amy Simonson, Andy Rose and Jarrod Wardwell contributed to this report.