‘The Town Was Torn Up’

At the Tecumseh State Correctional Institution in Nebraska, Seth Strasburg, 29, displays an imposing, biker-style presence. He has a shaved head, bushy chin beard and tattoos scrolled around his thick arms and neck, one of which quotes, in Latin, a Crusades-era dictum: “Kill them all. God will know his own.”

Beneath this fierce exterior, however, Mr. Strasburg, an Iraq combat veteran who pleaded no contest to manslaughter and gun charges in 2006, hides a tortured compulsion to understand his actions. Growing up in rural Nebraska, he read military history. Now he devours books like Lt. Col. Dave Grossman’s “On Killing: The Psychological Cost of Learning to Kill in War and Society” and Dr. Shay’s “Odysseus in America: Combat Trauma and the Trials of Homecoming.”

Because Mr. Strasburg is introspective, he provides a window into the reverberations of combat violence within one veteran’s psyche and from there outward. In Arnold, Neb., population 679, the unintentional killing last year by Mr. Strasburg of Thomas Tiffany Varney V, a pre-mortuary science major known as Moose, was a deeply unsettling event.

“To lose one young man permanently and another to prison, with Iraq mixed up in the middle of it — the town was torn up,” said Pamela Eggleston, a waitress at Suzy’s Pizza and Spirits.

In late 2005, Mr. Strasburg returned to Arnold for a holiday leave after two years in Iraq. Once home, he did not easily shed the extreme vigilance that had become second nature. He traveled around rural Nebraska with a gun and body armor in his Jeep, feeling irritable, out of sorts and out of place in tranquil, “American Idol”-obsessed America.

During his leave, he shrank from questions about Iraq because he hated the cavalier ones: “So, did you kill anybody? What was it like?”

He had, in fact, killed somebody in Iraq and was having trouble dealing with it. Like several veterans interviewed, Mr. Strasburg was plagued by one death before he caused another one.

In 2004, Sergeant Strasburg’s section was engaged in a mission to counter a proliferation of improvised explosive devices, or I.E.D.’s, on the road west of Mosul. One night, posted in an old junked bus, he watched the road for hours until an Iraqi man, armed and out after curfew, appeared and circled a field, kicking the dirt as if he were searching for something. Finally, the man bent down, straining to pick up a large white flour sack, which he then dragged toward the road.

“In my mind at the time, he had this I.E.D. hidden out there during the day and he was going to set it in place,” Mr. Strasburg said. “We radioed it in. They said, ‘Whatever, use your discretion.’ So I popped him.”

With others on his reconnaissance team, Mr. Strasburg helped zip the man into a body bag, taking a few minutes to study the face that he now cannot forget. When they went to search the flour sack, they found nothing but gravel.

“I reported the kill to the battalion,” Mr. Strasburg said. “They said, you know: ‘Good shot. It’s legal. Whatever. Don’t worry about it.’ After that, it was never mentioned. But, you know, I had some issues with it later.”

Mr. Strasburg’s voice broke and he turned his head, wiping his eyes. A reporter noted that he was upset.

“I’m trying not to be,” he said, then changed his mind. “I mean, how can you not be? If you’re human. What if I had waited?”

“Maybe I was too eager,” he added. “Maybe I wanted to be the first one to get a kill, you know? Maybe, maybe, maybe. And that will never go away.”

Which bothers him, Mr. Strasburg said, telling himself: “Get over it. You shot somebody. Everybody else shot somebody, too.”

Shortly after Mr. Strasburg’s military tour of duty ended, he returned to Iraq as a private contractor because, he said, he did not know what else to do with himself after eight years in the Army. “I have no skill other than carrying a gun,” he said.

By late 2005, home on leave, he was preparing to return once more to Iraq in January.

On New Year’s Eve, Mr. Strasburg, accompanied by his brother, consumed vodka cocktails for hours at Jim’s Bar and Package in Arnold. Toward evening’s end, he engaged in an intense conversation with a Vietnam veteran, after which, he said, he inexplicably holstered his gun and headed to a party. Outside the party, he drunkenly approached a Chevrolet Suburban crowded with young people, got upset and thrust his gun inside the car.

Mr. Strasburg said he did not remember what provoked him. According to one account, a young man — not the victim — set him off by calling him a paid killer. Mr. Strasburg, according to the prosecutor, stuck his gun under the young man’s chin. There was a struggle over the gun. It went off. And Mr. Varney, a strapping 21-year-old with a passion for hunting, car racing and baseball, was struck.

Asked if he pulled the trigger, Mr. Strasburg said, “I don’t know,” adding that he took responsibility: “It was my gun and I was drunk. But what the hell was I thinking?”

The Suburban drove quickly away. Mr. Strasburg jumped into his Jeep, speeding along wintry roads until he crashed into a culvert. Feeling doomed, he said, he donned his bulletproof vest and plunged into the woods, where he fell asleep in the snow as police helicopters and state troopers closed in on him.

Mr. Strasburg had never been screened for post-traumatic stress disorder. Like many soldiers, he did not take seriously the Army’s mental health questionnaires given out at his tour’s end. “They were retarded,” he said. “All of us were like, ‘Let’s do this quickly so we can go home.’ They asked: ‘Did you see any dead bodies? Did you take part in any combat operations?’ Come on, we were in Iraq. They didn’t even ask us the really important question, if you killed someone.”

After his arrest, a psychologist hired by his family diagnosed combat trauma in Mr. Strasburg, writing in an evaluation that post-traumatic stress disorder, exacerbated by alcohol, served as a “major factor” in the shooting.