I began my summer certain that innocent people are sometimes wrongfully convicted, but believing that when authorities are faced with irrefutable proof — DNA evidence, for instance — the innocent would go free; indeed, the government would practically trip over itself to rectify its mistakes. I was wrong.

I was a communications intern at the Innocence Project, an organization that works to free wrongfully convicted prisoners using DNA evidence. The group represents inmates and lobbies to stop wrongful convictions from occurring. Now in its 20th year, the Innocence Project has played a key role in most of the 300 exonerations through DNA evidence in the United States.

Early in my internship I learned about the case of George Allen. You could hardly imagine someone sitting in prison who seemed less guilty. Allen alleges that police arrested him by accident when they confused him with a suspect in a rape and murder case. They discovered their mistake, but decided to interrogate the drunk and schizophrenic Allen anyway. A recording shows police guiding him to answer questions in a way that would incriminate him. Nonetheless, Allen was convicted of the rape and murder in 1983. It wasn’t until 2011 that testing revealed that Allen’s DNA didn’t match semen found on the victim’s clothing.

In many ways, Allen’s case is a common one for the Innocence Project. But here’s the thing about Allen: he’s still in prison. In spite of the evidence demonstrating his innocence, the Missouri Attorney General’s Office refuses to release him. They have been “reviewing” his conviction for almost a year, while for nearly 30 years, he’s been behind bars.

Of the many troubling aspects of this case, the most disturbing is that authorities appear to have known that Allen was innocent since his conviction in 1983. According to the petition for Allen’s release, the serology expert discovered that semen from the crime was of a different blood type than Allen’s, yet the expert crossed this finding off the report. In the last year, police have admitted that their interrogation was “iffy,” that it included “leading questions,” and that they did not turn over all the evidence to the defense, including fingerprint evidence that further demonstrates Allen’s innocence.

I turned to an employee who sat behind me. I said something to the effect of, “Can you believe this?” She responded, “Yeah, it’s terrible.” She sounded sympathetic, yet unsurprised. She had, after all, worked at the Innocence Project for a few years, and no doubt had seen this sort of bureaucratic intransigence more times than I could fathom.

“But they’re going to have to let him out, aren’t they?” I pressed.

“They’ll let him out eventually,” she replied. “They’re just stalling for time.”

Part of the reason police have stalled is sheer embarrassment. When an inmate is exonerated, the headlines are everywhere. Press on prosecutors and police can be fatal to careers. On the other hand, when even someone like Allen is still in jail, the stigma of conviction can sew doubt in the public mind. Under those conditions, prosecutors have every reason to stall or even hide evidence.

These tactics came to light during the case of Bruce Godschalk, who was convicted of two counts of rape in 1987. When the Innocence Project demanded DNA re-testing, the prosecution lied in three different ways: first, they claimed that the evidence had already been tested, then that the results had been inconclusive, and finally that the evidence had been destroyed in the course of the testing. But it turned out that testing had never taken place; the same police officer who had coerced Godschalk’s false confession failed to deliver the samples to the lab for testing. All of this took months to emerge, but when the evidence was finally tested, it cleared Godschalk. He was released on Valentine’s Day in 2002.

These are the obstacles the Innocence Project encounters, and its work only gets harder as the American prison population grows: 2.27 million adults are currently incarcerated, nearly twice the number from 20 years ago.

Each exoneration is a success, but each is also a failure — a failure of the criminal justice system. The Innocence Project is “part of the criminal justice system,” says one of the Project’s staff attorneys, Olga Akselrod, but “by the time the cases get to us, they’ve been an example of total system failure.”

Policy Director Stephen Saloom agrees. “The most important role our work has played is to force people to recognize the uncomfortable truths of the system’s fallibilities,” he says.

At any given time, the Innocence Project is evaluating 6,000 to 8,000 potential cases and representing 300 active cases. Any one of these people might be innocent, but the chances of their exoneration are extremely slim. After a summer of work, the Innocence Project showed me an underside of the justice system that I hadn’t known existed. It showed me a world in which prosecutorial egos and bureaucratic red-tape can hinder justice, even in the face of hard evidence. Above all, it showed me the importance of continuing to fight for the truth.