(CNN) The Oklahoma citizens who sentenced Richard Glossip to die are just like you and me -- ordinary folk. As fact finders, they are supposed to receive all the information they need to make an informed judgment. So if facts are falsified or withheld, crucial evidence goes missing or key witnesses lie, the jury's decision will inevitably be skewed. They can only work with what they're given. Unfortunately for Richard Glossip, what the jury did not know could mean an innocent man is executed later this month .

Of the 155 people exonerated off death row 10 of whom were tried in Oklahoma ) most were wrongly convicted because their jurors received incomplete or misleading information at trial. This, I'm convinced, is what has happened to Richard Glossip, who is scheduled to be put to death today, Sept. 30, unless his pro bono lawyers can surface witnesses and evidence to get him a hearing in court.

I'm involved in the effort to save his life because I am convinced he is innocent. I wrote to him and then spoke to him, and during that first phone call he asked me to be with him if he's executed. Sadly, this isn't the first time I have been asked to perform this duty . In fact, I've already accompanied six people to execution, two of whom I'm convinced were innocent. I've seen our justice system up close. And I've seen how broken it is.

How did Glossip end up on death row in the first place?

On January 7, 1997, Barry Van Treese, the owner of the Best Budget Inn in Oklahoma City, was bludgeoned to death by a man, Justin Sneed, who confessed to the killing. However, he claimed that Glossip, the manager of the motel, had offered him money to kill Van Treese. The jury apparently believed Sneed's testimony, and despite the Oklahoma Court of Criminal Appeals in 2001 describing the evidence in the first trial as "extremely weak," the decision was affirmed by the U.S. Court of Appeals in 2013

As a result of all this, the person who actually committed the murder is now serving a life sentence in a medium security prison, while Glossip, convicted of "murder-for-hire" -- almost solely on Sneed's word, and in the absence of physical evidence from the scene -- now faces death by lethal injection.

It shouldn't be this way. And if the jury had been given access to some key information, it probably wouldn't be.

So what didn't they hear at the time?

For a start, Sneed, age 19 when he was arrested, only saw his attorney once in the first six months he was in custody. Plus, during the police interrogation and his trial testimony, Sneed gave several contradictory versions of what took place . In fact, Sneed gave several versions of the story in his initial police interview.

It is almost impossible, then, to see Sneed as a reliable witness. And without his testimony, it is exceedingly doubtful that the prosecution would have been able to obtain a guilty verdict against Glossip, much less a death sentence.

The jury in both trials also didn't get to see Sneed's taped confession , which for some reason wasn't shown in court. As the video clearly shows, the police made clear they didn't believe that Sneed was acting alone, before finally revealing that they had arrested Glossip. They went on to press Sneed on whether the "whole thing" was his idea.

Another key point I'm sure the jury would like to have been aware of is that Sneed told others before the trial that when he killed van Treese, he was coming off a "two-day meth run." This would have added additional weight to Sneed's admission that he "hustled" to get money for drugs, and it would have presented a clear motive for robbing Van Treese.

Finally, a worker at the motel testified that Glossip was manipulating the books, something that documents submitted after the conviction show wasn't the case. It appears that having no solid forensic evidence to corroborate Sneed's accusations, the prosecution had no choice but to show that Glossip had a compelling motive to have van Treese killed. The theory proffered was that Glossip stole from his boss and thus feared for his job if the truth came out.

But there is also a sinister realm of unfairness in capital cases, where exculpatory evidence "goes missing."

In this case, it was motel receipts that supposedly were lost in a flood. And there was the shower curtain and duct tape that Sneed claimed he and Glossip used to cover the motel window that was broken during the struggle. Had the curtain and tape been presented as evidence, the jury might have heard that they contained only Sneed's fingerprints, not Glossip's.

Finally, the jury did not get to see the surveillance video from the Sinclair gas station across the street where Sneed went the night of the murder -- as did a man staying at the motel, who left in the early morning hours in such a rush that he left behind his luggage. Common sense would suggest this man should at least have been a suspect, but he was not identified nor questioned.

There was so much that the jurors never knew. The fact that Richard Glossip is facing imminent death based on such flawed and threadbare evidence shows just how broken our court system is. And the case is also a betrayal of the constitutional ideal of fairness that we all cherish, and of a group of people summoned to pass life-or-death judgment. They will be forced to live with the question and possible doubt that they may have sentenced to death an innocent man.