The first time I met Spc. Shane Parham, his face was wrinkled with sadness. Beads of sweat met Iraqi dust and curved down his sunburned skin like the swampy Alcovy River in his native Georgia.

He was in the checkout line at Baghdad's Camp Striker commissary, only two months into his Iraq tour. But already, he'd witnessed war's brutality.

I thought of that first meeting recently as I peered at Parham through a 2-inch thick slab of glass in a prison visitation booth. The cinder-block walls, drab like the Iraqi desert, closed in on him.

Gone was his Army uniform. Instead, he wore tan prison garb, his hands bound in cuffs. His nails were long, his beard scraggly. He was not allowed to trim or shave for fear he might turn sharp instruments against himself, though he had once been chosen to man an M203 grenade launcher.

Tears trickled out of his tired blue eyes, no longer bright and full of promise.

He was a hero, honored by the governor of Georgia. Now the former sheriff's deputy was sharing quarters with thieves, addicts, even murderers.

I'd met him in July 2005, in the midst of a raging insurgency in Iraq. He was a soldier's soldier, used to carrying loaded guns and wearing bulletproof vests. Brawny. Proud. Someone who hunted the game and fowl he put on the Sunday table.

He'd arrived in Iraq ready to fight, heady with adrenaline. But now, four of his friends were dead.

At first, he couldn't even talk about what had happened. But in time, he would unload his tale of loss, sitting in a tent with head in hands, struggling for words to describe the unspeakable.

I knew it would be a long time before he healed. But neither of us could have predicted he would end up behind bars.

His yearlong tour cut short by injury, Parham only served seven months in Iraq. But, as he learned, it's not the length of time at war that can change a man, but what he experiences.

He came back to tiny Social Circle, Georgia, and tried to restart life, like the 2.2 million others who've returned from Iraq and Afghanistan. Of those, 43,000 came home without limbs or with other physical wounds, according to icasualties.org, which tracks combat deaths and injuries. One in five struggles on the inside.

They come back scarred by hidden wounds, such as post-traumatic stress disorder and traumatic brain injury. They fight the war on a second front, in the cities and homes of America.

A Department of Defense task force last year acknowledged the enormous physical and psychological demands placed on service members in two of America's longest-running wars. The group reported that more than 1,100 members of the armed forces took their own lives between 2005 and 2009, though it's not clear how many had been deployed. But the number represents an average of one suicide every 36 hours.

There are no definitive statistics on how many soldiers wind up in court because of their troubles. But the anecdotal evidence is strong: From New York to California, from Colorado to Georgia, veterans of Afghanistan and Iraq have been charged with crimes as serious as murder.

The re-entry counseling now required of returning soldiers warns that alcohol and drug abuse and domestic violence are precursors of even more dangerous behavior, especially when support systems erode.

But for many veterans, like Parham, the warnings aren't enough.

In Iraq, he could not come to terms with what he had seen and done. In Georgia, he could not stop thinking about it.

"I just got so twisted up. I was angry and too embarrassed to ask for help," he said from the other side of the visitation window.

Six years ago, I had watched him gear up in full battle rattle. He looked menacing with grenades and ammo hanging from his flak jacket and night vision goggles strapped to his helmet. He climbed up into the gunner's hatch of his Humvee as his platoon rolled out in the darkness of night.

Every time, the soldiers prayed before leaving Camp Striker. They never knew what lay ahead, whether they would live or die.

Now, Parham, 35, rose from his metal seat at the Newton County Detention Center to return to a jail cell the size of a pickup bed. Here, too, he did not know what lay ahead. He didn't know whether he would survive an enemy within.

Six days, and eight dead

It was late July 2005, and the Baghdad summer was melting even the hardiest Georgia boys.

Parham and his friend, Sgt. Bill Jones, waited ahead of me in a slow-moving cashier line at the Camp Striker PX. We had just come back from a practice run for a memorial ceremony for four soldiers killed July 24 by a massive bomb hidden in the road.

I recognized Parham from the honor guard. His commanders picked him for that solemn duty because of his experience as a sheriff's deputy in Walton County, Georgia. "I'd like to talk to you about what happened," I said tapping him on the shoulder. "Did you know the four guys who were killed?"

He said they were all from his company. Then, he whipped out a small notebook and an all-weather Army pen and took note of the number of my tent: 535. It was one of hundreds that dotted Striker, a transient camp adjacent to the Baghdad airport and home to the 48th Infantry Brigade.

The Georgia guardsmen had not seen combat since World War II. But in the Iraq war, with no military draft in place, the citizen soldiers of the National Guard were heavily relied upon. Many were like Parham -- law enforcement officers whom the U.S. Army considered perfectly suited for a war in which counterinsurgency operations meant mixing with the local population to develop trust, just as police do in the United States.

Parham had policing and patriotism pulsing through his veins. His father served in Vietnam, then made a career as an Atlanta policeman. His grandfather fought in World War II.

This was his second stint as a soldier. He'd enlisted in the Guard once before, when he was 16. At 18, he got a job as a jailer and worked as a police officer before becoming a sheriff's deputy. He re-enlisted, like so many Americans, after the September 11 terrorist attacks in 2001.

His wife, Wendy, had feared he would be sent overseas. But he insisted; he couldn't bear the thought of not being able to tell his daughters that he had done all he could to defend his country.

What mattered most to him were family, God and country -- in that order.

I wanted to ask Parham a thousand questions. What had he seen out there, beyond the heavily guarded gates, in the villages where friend was indistinguishable from foe? What did it feel like to lose a buddy to an unknown enemy?

"Nice meeting you," he said, tucking his notebook back in one of the many pockets of his uniform. He put his booney hat back on his head and walked out of the Striker PX.

The following evening, I watched him at the memorial. The entire battalion was there, on rickety wooden bleachers and plastic chairs. Each soldier walked up to the four dog tags dangling from upended rifles and four pairs of desert boots representing the men who had died.

Parham wore his game face and fired his M-16 ceremoniously in salute to the dead. He showed no sign that he was mangled inside.

Days later, death visited Parham's company again. Four more were killed on July 30 in the same cruel fashion.

One minute, the three-Humvee convoy was on routine patrol on a road near the base. The next, a thundering boom tore away the guts of the third vehicle. When the smoke settled, the only thing that was recognizable was the engine block and the front and rear axles.

Parham was out on patrol with his squad when a frantic young lieutenant's voice crackled over the radio.

"It's not here. I can't find Anderson's truck," he said, referring to Sgt. 1st Class Victor Anderson, who just three days before had eulogized his fallen soldiers.

Anderson's was the third and last vehicle in the convoy. It was blown to bits by a 500-pound bomb.

Parham's squad rushed to the scene. The brigade commanders ordered them to stand by while Army explosives experts ensured there were no other bombs in the area. Only then would it be safe for Parham and the others to recover the bodies of their friends.

Hours passed. Maybe nine or 10. Maybe more. Night turned into day.

When he returned to base, Parham knocked on my door. The air was thick with heat and the acrid fumes of Baghdad burning. He rolled in like a shamal, the blinding desert dust storms that hold Iraq hostage in the summer. He smelled like an infantryman -- of sweat, blood, cigarettes and spent ammo.

He barely fit into the folding camp chair, heaving from side to side, his rifle still slung over his shoulder.

"I don't know where to begin," he said.

"I seen some bad things. Bad. I mean, I can't describe it."

He was fighting tears.

"I just want to get back to see my girls," he said, avoiding what he wanted to say.

Bailey was 7; Cammi, 5. Laynni was just a baby, growing up without her daddy beside her. If only he could return to his 54 acres on Clegg Farm Road and spend the rest of the summer trout fishing with his daughters.

But his tour had just begun.

He cradled his shaven head in his hands, the way a mother holds a newborn. An uncomfortable period of silence passed. I didn't know whether I should break it. Finally, he did.

"I had to shoot the dogs," he said.

"Dogs?" I fumbled to understand.

He meant the stray dogs that were gnawing at his friends' body parts, strewn about the road with bits of Humvee and fuel. He could not forget the smell; he recognized the odor from a plane crash in Walton County many years before. Charred human flesh.

He put on gloves so he could pick up the pieces and put them in body bags for their final journey home. The night before, he'd had dinner with these guys, joking about getting blown up, trying to overcome the grief that had befallen them after the first four died.

In the days ahead, I visited Parham's platoon in their tent. They were surrounded by eight empty canvas cots, each stripped of sleeping bags and all of the things that once belonged to ordinary men from Georgia -- a truck driver, a cop, a construction worker.

The survivors shifted on their cots and scanned the dusty canvas innards of the tent. They were all like Parham. They'd seen their share of the thorny side of life. But they had never seen "crap like this."

Jones told me his men were balancing grief and anger. All they wanted was to get the bastards who killed their friends.

Many years later, in jail, Parham would say he did not realize it then, but the Iraq war instilled malice and hatred in his heart that drove him to do things for which he could never forgive himself.

Or worse, God would never forgive him.

That, he believed, was why he lost everything.

Vengeance and hope

The soldiers in Parham's platoon were allowed to go home early on a three-week leave that usually came midway through deployment. Parham returned to the serenity of life in Social Circle and dreaded the day he would have to return to Iraq.

So much had changed since the brigade's departure in May. His ideals of fighting an honorable war had fallen to the wayside. This time when he got back on the plane, he knew well the dangers he faced.

Our long conversations began when he resurfaced at Striker. Summer was gone and the 80-degree September evenings seemed chilly. Soldier and journalist occupied a splintered picnic bench plopped down on a field of gravel.

He smoked Marlboro after Marlboro and interspersed stories of line dancing with taking aim at suspected insurgents. It was a curious mix of fun and horror. But that's how his mind worked. Here, there, and back to here.

Anger coursed through him. He talked about avenging the deaths of his eight comrades.

He thought it was unfair that he had been trained to kill, only to find that in Iraq, the enemy was invisible.

"I looked for an enemy everywhere, whether there was one or not," he would tell me later. "Some of us got pretty vigilante. It was our way of survival."

Before I left Iraq that fall, Parham gave me a CD filled with photographs he shot with his point-and-shoot camera.

Snapshots of Iraq's children popped up on my computer screen. They were dirty and malnourished and dressed in tattered dresses and pants.

He said the kids reminded him of his own. One day, he thought, maybe his girls would meet the kids of the men who killed his buddies. One day, he thought, the madness of war would end.

The enemy in sight

In October, I flew back home to Atlanta. A few days after I left Baghdad, Parham experienced the battle of his life. I would find out about it a year later during a conversation over lunch.

He was reluctant to tell me details.

"I don't want to get anyone in trouble," he said. "You gotta understand why we did what we did."

He was struggling to come to terms with the way his unit had treated suspected insurgents, their desire for vengeance. That was no way to fight a war, he said.

Restraint had always been Parham's priority as a law enforcement officer. He had never used unjustifiable force. But in Iraq, he adopted a different ethic, shaped by the nature of the war.

"There were many times over there I could have used restraint," he told me. "But I chose not to. I was so angry."

Alpha Company Humvees regularly patrolled Al Salam, a village on the outskirts of Baghdad. On this day, a platoon got ambushed in the center of the village.

Parham's squad was conducting house-to-house searches in the area. They dropped everything and rushed to help the guys under attack.

Finally, there was an enemy in sight.

Parham's men engaged with insurgents on rooftops. They hunkered down near their vehicles in a hail of AK-47 fire.

Some, like Nick Hamerla, had never been shot at before. He was only 20 and looked up to Parham. He wanted to go back home and become a law enforcement officer, too.

Hammer, as he was called, thought Parham had taken the deaths of the eight soldiers especially hard and become more withdrawn than his comrades. He said that after those horrific July nights, Parham never joked with him as he had during months of training at Fort Stewart and in their first few weeks in Iraq.

The firefight at Al Salam that day went on for an hour, though it felt endless to Alpha Company. Shots rang out from every corner of the village, even from the mosque minaret.

All Parham could hear was that familiar snapping sound of bullets. All he could see was the dirt flying off the ground.

Parham fired a lot of rounds. Everyone did. The soldiers were convinced the insurgents were using women and children as shields.

"Imshi! Imshi" Parham shouted to a woman in Arabic, meaning "get back."

Hamerla was trying to get more ammo from his Humvee when he got caught in the fire. He dropped his rifle and hugged the dirt.

"Hammer!" Parham yelled.

Desperate, Parham took out his grenade launcher and lobbed a lethal round to a rooftop where snipers were taking aim at his squad. Everything went quiet. The shooting stopped.

Hammer was OK. So were the rest of the guys.

Alpha Company soldiers said no civilians were killed that day but Parham believed they were.

"Thou Shalt Not Kill." It's in the Bible. Parham thinks he killed the innocent, that he took something precious from another man.

He thought of his own wife and daughters. He did not know it then, but soon he would see his family. The reunion would take place with Iraq still raging in his head.