In a jail in Phoenix, Arizona sits Inmate P382209--Clark Fish. Clark is 24. He is wearing black and white stripes that suggest a different era of incarceration. Young, good looking, with sandy blond hair, well spoken in a self-educated way, he does not give off the impression of a hardened criminal. Clark is in his 16 by 9 cell taking two pink socks (the inmates have pink undergarments in the Maricopa County facility) and symmetrically rolling them together into a little ball about the size of an orange. He finishes by making and adjusting the dimple impression where the socks come together into a perfect curve--or, as my drill instructor used to say when I was in Officer Candidate School, "I want those socks to smile, Candidate Larsen! Why is the goddamn smile on those socks crooked?"

Clark's perfectly folded socks were a tell tale sign that he had once worn a different uniform than the old-school stripes he wears today. Just four years ago he was an Army medic deployed to Iraq. Thanks to his former military training his socks contain the perfect smile--but Clark does not. He finds himself in the most grave of circumstances: convicted of first-degree murder for strangling his girlfriend and now facing the death penalty.

In June of this year, after two-and-a-half years awaiting trial, Clark was found guilty. He joined the growing ranks of veterans from the wars in Iraq and Afghanistan who return home and commit crimes. As I found in "War Crimes," my new Vanguard documentary, one common thread among these fallen heroes is that a large majority of them are suffering from PTSD, or post-traumatic stress disorder. [Watch a trailer for "War Crimes" here.]

Clark was diagnosed with PTSD, which encompasses a wide array of long-lasting physical and mental responses to experiencing trauma, in 2007. To date over 350,000 veterans have been diagnosed with the condition and a recent Stanford University study suggests that as many as 770,000 of those returning from the two wars overseas may be suffering with PTSD.

As I followed the case of Inmate Fish, who had served six months at Balad Air Base in Iraq, I began to wonder just how many other veterans with PTSD from Iraq and Afghanistan were, like Clark, spending time behind bars. The answer is unknown. Neither the Department of Justice, nor the Department of Defense, nor any institution has an accurate count of how many vets are in our nation's prisons and jails. It is troubling that the scope of this problem is not understood.

The anecdotal evidence points to an iceberg-sized trend looming beneath the surface. Dozens of soldiers have been accused of killing girlfriends or wives, a town in Colorado had eight murders within a single battalion, and there is a landmark case in Oregon where an Iraq vet used PTSD as a defense for murder. In a yellow ribbon political climate, asking questions about incarcerated veterans is a sticky issue. But as I started looking at small town newspaper articles and speaking to advocacy groups, the pattern was undeniable: veterans are getting arrested and getting locked up.

In 2008 The New York Times published an article on Iraq/Afghanistan veterans who had been charged with murder after returning home. The researchers, using Lexis-Nexis and culling reports from local papers, determined that there had been at least 121 murders by veterans since the start of the two wars. The report was an initial indicator of a problem--but it may have underestimated the size and scope of the issue. The research technique only flagged articles where the veteran's status was explicitly mentioned. A case such as Clark Fish's, where there was no mention of his military service, did not make the tally. We were able to determine that there have been at least 44 additional murders since the article was published two years ago. While high-profile murders are headline grabbing, they represent only the apex of a pyramid of crime committed by veterans, including domestic violence, drug use and DUIs. The sum total of crimes committed by veterans is even more striking.

For the most part the military denies a connection between crime and combat, the tacit suggestion being that among any population there is going to be a certain amount of crime. However, the rate at which veterans are committing crimes wildly outpaces the general population. A series of articles by Dave Phillips, a local reporter from the Colorado Springs Gazette, about a battalion known ironically as the "Lethal Warriors" in Ft. Carson, Colo., documents one unit of about 500 soldiers in which eight men were charged with murder. Statistically that is about 500 times greater than the average murder rate of the city where the crimes occurred. In all the cases in Colorado--and in the case of every veteran we spoke with who had spent time in jail--PTSD had played a role in the crime.

So what's happening here? Why are a growing number of veterans linked by their service and their PTSD ending up behind bars? The pattern we observed seemed to follow a typical downward spiral. A veteran suffering from PTSD doesn't seek or receive the treatment he or she needs. They begin self-medicating to deal with PTSD, abusing alcohol, prescription drugs, and illegal drugs, and eventually getting in trouble with the law. These first offenses are early warning signs that go unheeded. Then, in many of the cases, the smaller offenses lead to larger offenses--like murder.

What is troubling about this trend is that the scope is not understood. Some experts have suggested that there is a lag effect of about five years between veterans returning and a follow on crime wave. They predict, eerily, that we are at the leading edge of a "tsunami" of veteran crime. Perhaps even more disturbing is the dearth of data and conversation about the subject.

Ultimately we ask our veterans to do an incredibly difficult thing. We ask them to go to a war and deal with the reality of death, destruction, and despair--and then to return home and put those things behind them, to fully function as members of society. Imagine spending 15 months overseas and never leaving your rifle. Sleeping with it, eating with it, even taking it to the john. You are trained to never be without it. Then you come home, and you feel naked without it. So you do what you where trained to do and carry the weapon at all times. Only now, if you bring your weapon to a movie theater, you may have committed a crime. In many of the cases, having a weapon on them was a critical component of a veteran being charged with a crime. Compounding that adjustment, many of these returning veterans are also suffering mental health injuries. The explosive cocktail of PTSD, self-medication, and combat experience has proven in some cases to be a violent combination.

This problem may have been pre-empted by forethought. America has ample evidence of returning soldiers damaged by war. In the early 1980s, one in five prisoners in America was a Vietnam veteran. Hollywood registered the trend. In Rambo: First Blood a small town sheriff arrests a Vietnam veteran. Homer chronicles Ulysses' struggle to adjust to coming home after a decade of war. Yet despite the prevalence of literature and pop culture precedent, the military and the Veterans Administration seem to have been underprepared to deal with a generation coming home after the current conflicts.

The news is not all bad. There are some encouraging signs. Veteran's Courts around the country are being established to focus on treating veterans for their PTSD rather than punishing them for their crimes. A positive step, but simultaneously an indicator of the problem at hand. The VA is getting better at identifying and treating the invisible wounds of war. Certainly the key to solving the issue is to identify vets suffering from PTSD before it spirals into criminal behavior. And a few voices within the military are reluctantly starting to acknowledge the issue. The former Commanding General of Ft. Carson, one of the epicenters of the PTSD and crime epidemic, spoke of the "crescendo effect"--the idea that lesser crimes like DUIs and assault are red flags for further trouble. The critical issue remains: we have neither a comprehensive tracking system nor an adequate plan to receive the hundreds of thousands of veterans who are suffering from PTSD and may be at risk for ending up in jail or prison.

I have a close friend, a fellow veteran, who talks about the difference between the aftermath of WWII and Vietnam. He says, "After World War Two, a whole generation of soldiers came back home and built up their country. Conversely, we can acknowledge that after Vietnam many veterans returned and struggled to find their place." The battle for how this new generation of veterans will be remembered is still up for grabs.

While it's important to emphasize that the vast majority of veterans return home after serving honorably and re-integrate into society using many of the skills and strengths of their military service, the last several months have taught me that an increasingly alarming number are unable to leave the war behind. For the most extreme cases, PTSD is rapidly becoming a pipeline to prison. From Clark Fish who faces the death penalty in Arizona, to Jessie Bratcher, who was found guilty but insane because of PTSD in Oregon, veterans are fighting difficult battles in the courtrooms.

What steps we take to prevent other soldiers from becoming embroiled in these tragic scenarios will help define how this generation of veterans returns home and move from soldiers to citizens. We help the entire country by helping veterans who are on the edge. It makes our communities safer and honors the values they fought for.

After the jump, meet Inmate Clark Fish in this exclusive clip from Vanguard's "War Crimes," premiering Wednesday, July 7 at 10/9c on Current TV.