Introduction May 18, 2010

On Nov. 30, 2007, 24-year-old Kevin Shields went out drinking with three Army buddies from Fort Carson, Colo., a base on the outskirts of Colorado Springs. A few hours later, he was dead -- shot twice in the head at close range and left by the side of the road by his fellow soldiers. Shields' murder punctuated a string of violent attacks committed by the three, who are now serving time in prison for this and other crimes, and it contributed to a startling statistic: Since the Iraq war began, a total of 18 soldiers from Fort Carson have been charged with or convicted of murder, manslaughter or attempted murder committed at home in the United States, and 36 have committed suicide.

In The Wounded Platoon, FRONTLINE investigates a single Fort Carson platoon of infantrymen -- the 3rd Platoon, Charlie Company, 1st Battalion, 506th Infantry -- and finds, after a long journey, a group of young men changed by war and battling a range of psychiatric disorders that many blame for their violent and self-destructive behavior. Since returning from Iraq, three members of the 3rd Platoon have been convicted on murder or attempted murder charges; one has been jailed for drunk driving and another for assaulting his wife; and one has attempted suicide.

The FRONTLINE investigation also uncovers extraordinary footage from police interrogation tapes alleging that members of the platoon murdered unarmed Iraqis. "There's a whole bunch of people in the unit that killed people they weren't supposed to," according to Bruce Bastien, who, along with Louis Bressler and Kenny Eastridge, is now serving time for the murder of Kevin Shields. In a stunning confession recorded by police interviewers and shown for the first time on television, Bastien admits to his role in the murder of two U.S. soldiers and the stabbing of a young woman during a robbery in Colorado Springs -- and he makes claims about more murders committed in Iraq during the surge. "It's easy to get away with that kind of s*** over there. You can just do it and be like, 'Oh, he had a gun,' and nobody really looks into it. 'F*** it, it's just another dead Haji.'"

While the Army has concluded that there is no evidence to back up Bastien's allegations of soldiers killing innocent Iraqis, FRONTLINE also speaks with platoon member Jose Barco, who makes a similar claim. "We were pretty trigger-happy," he says of the soldiers' time in Iraq. "We'd open up on anything. We usually rolled three or four trucks, and if one of them got hit and there was any males around, we'd open up, and we'd shoot at them. ... They even didn't have to be armed."

Barco is now serving a 52-year prison sentence for attempted murder following an incident at a party in Colorado Springs. Once hailed as a hero for saving two soldiers during a suicide-bomb attack that left him with a traumatic brain injury, or TBI, he was also diagnosed with post-traumatic stress disorder and says he was prescribed nine different medications. FRONTLINE interviews retired military psychiatrist Stephen Xenakis, who says that there may be a link between Barco's crimes and his injuries. "We have someone who's been emotionally traumatized, and they've got PTSD. They're anxious, and they're depressed, and they've got TBI, which means that they've got problems in decision making. They can't think as clearly. They are really vulnerable to just overreacting."

In The Wounded Platoon, FRONTLINE reveals a military mental health system overwhelmed with soldiers suffering psychological injuries from the surge -- at Fort Carson the rate of PTSD diagnosis has risen 4,000 percent since 2002 -- and the widespread use of prescription psychiatric drugs both at home and in combat. "Everybody was on Ambien, everybody. It was hard to find somebody that wasn't taking Ambien," says the 3rd Platoon's medic, Ryan "Doc" Krebbs. "It helps you sleep, and it also f***s you up. It gets you pretty high." After returning home, Krebbs was also prescribed the antipsychotic medication Seroquel, on which he would purposefully overdose in a suicide attempt. "I thought that my time in this place was over, and I'd already done what I was supposed to do, and I didn't want to live anymore."

Before the Iraq war, American soldiers in combat zones did not take psychiatric medications, but by the time of the surge more than 20,000 U.S. troops in Afghanistan and Iraq were taking antidepressants and sleeping pills. These drugs enable the Army to keep soldiers with post-traumatic stress disorder on the battlefield. "What I use medications for is to treat very specific side effects," Army psychiatrist Col. George Brandt tells FRONTLINE. "I don't want somebody in a helplessness mode in a combat environment. I want to make sure I don't have someone with suicidal thoughts where everyone is armed."

Kenny Eastridge, who is now serving time for the murder of Kevin Shields and other crimes, tells FRONTLINE that he sought help for mental health problems from a combat stress center on Forward Operating Base Falcon. "I was having a total mental breakdown. Every day we were getting in battles and never having a break. It seemed like, it was just crazy," he says. "They put me on all kinds of meds, and I was still going out on missions. They had me on Ambien, Remeron, Lexapro, Celexa, all kind of different stuff."

Despite the warnings that patients on these medications should be closely monitored for side effects, Eastridge was sent to a remote combat outpost for weeks at a time with no medical supervision or mental health provision. He says he ran out of medication and was also smoking marijuana and taking Valium. In dramatic footage filmed by other members of the 3rd Platoon, FRONTLINE shows Eastridge behaving erratically, wandering into Iraqi homes, lying in their beds, and trying to hug local women and men.

Fort Carson's hospital remains understaffed with almost a quarter of its psychiatry positions unfilled. The 3rd's battalion, which has been reflagged as the 2-12 Infantry, is about to return home from a year of intense combat in Afghanistan. "We're all wondering what's going to happen," says Colorado Springs psychotherapist Robert Alvarez. "It's a scary thought, you know, what's going to happen in this community. Are we going to have more murders? Are we going to have more suicides, or are we going to have more crime? I think the answer to that is probably yes."