Richard Glossip, an Oklahoma man accused of murdering his boss in 1997, has spent 25 years in prison, awaiting his execution while maintaining his innocence.

Now, 34 Oklahoma legislators and Glossip’s attorney are petitioning to help the 59-year-old get a new hearing after the Reed Smith law firm recently released an independent, 340-page report alleging that Glossip's murder-for-hire conviction and death sentence are unsubstantiated. 

"We’ve been very frustrated for quite some time because we now have all of the evidence that we requested … from an independent investigator. That's 3,000 hours looking at this case. These are highly trained, highly paid lawyers from a big law firm," attorney Don Knight told Fox News Digital.

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He added that those advocating for Glossip need to tell "anybody who will listen" in the state of Oklahoma, including the "attorney general or the governor," to "do the right thing and let this evidence be presented in court."

The Reed Smith law firm recently released a 340 report detailing new evidence in Richard Glossip's case

Oklahoma Death Row inmate Richard Glossip (Fox News Digital)

The next step, Knight said, is for Oklahoma Attorney General John O'Connor to respond to the petition.

Glossip’s execution has been delayed three times, and his next death date is scheduled for September 22. 

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Glossip was sentenced to death in the 1997 murder of Barry Van Treese. Prosecutors allege that Glossip killed Van Treese, the owner of a motel where Glossip worked as a manager, by convincing a then-19-year-old maintenance worker, Justin Sneed, to execute his killing.

Sneed is serving a life sentence after pleading guilty to beating Van Treese to death with a baseball bat in 1997 in a room at the Oklahoma City motel owned by Van Treese. Sneed testified that he killed Van Treese, but only after Glossip, the motel manager, promised to pay him $10,000 to commit the crime.

Richard Glossip's execution is scheduled for Sept. 25.

Oklahoma Death Row inmate Richard Glossip (Oklahoma Department of Corrections via AP File)

But Knight, Republican Oklahoma state Rep. Kevin McDugle, 33 other Oklahoma state legislators and advocates for Glossip claim that he was wrongly accused after an investigator allegedly convinced sneed to incriminate Glossip in his testimony. Knight also alleges that prosecutors in the case destroyed or lost evidence that could have apparently changed Glossip’s fate. 

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"I can't find one shred of evidence to stand up in court today," McDugle said. "If the jury had seen how the investigators led Justin to … [point] the finger at Richard, he would not be on death row today. I mean, it is an unbelievable case."

McDugle said he was inspired to start looking into the case after watching the "Killing Richard Glossip" documentary, and he believes the case should at least be re-examined.

 Oklahoma County District Attorney David Prater to respond to the petition to review Richard Glossip's case.

Oklahoma Death Row inmate Richard Glossip (Fox News Digital)

"There's a lot of stuff in [the report] where you just you read it, and you're like, I don't know how anybody could say, ‘Yeah, beyond a reasonable doubt, this guy did it,’" McDugle said.

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The Reed Smith law firm’s report into Glossip’s case concludes that the twice-convicted man’s "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."

"Considering the facts we uncovered, and that there exists no physical forensic evidence or credible corroborating testimony linking Glossip to the crime, our conclusion is that no reasonable juror hearing the complete record would have convicted Richard Glossip of first-degree murder," Reed Smith partner Stan Perry said in a June statement after the report was released.

The Associated Press contributed to this report.