JOHN DAY, Ore. — - When Jessie Bratcher's fiancee told him the baby might not be his, that she had been raped two months earlier, he went quiet.

The former Oregon National Guardsman hung his head for the longest time. Then he went into the next room, put the barrel of an AK-47 into his mouth and took it out again.

He told Celena Davis not to expect to get any sleep that night. He walked up to her with a pair of scissors and slowly cut off her hair.

Two mornings later, they drove to the hardware store. While Davis waited in the truck, Bratcher went in and bought a gun. He came out, loaded it and asked: Do we go to the police? Or go find the guy?

"Police," Davis said.

Except that it was a Saturday, and the main door to the station was locked. Bratcher and Davis didn't know there was an emergency door on the side of the building.

So they headed for Jose Ceja Medina's trailer.

At first Medina, standing on his porch in running shorts, denied knowing Davis. Then he said they'd had sex, but that he hadn't raped her, and he offered to take care of the baby.

He ended up with six hollow-point bullets in him.

At Bratcher's murder trial, the district attorney argued that the 27-year-old one-time grocery clerk had hunted down and killed Medina.

But Bratcher's lawyer said that when his client held the gun that morning, he was more than a furiously jealous boyfriend. He was a trained killer who'd been taught by the Army to mow down threats without much thinking, a man whose diminutive stature, quiet politeness and once-cheerful nature disguised the fact that he was, in the words of a sociologist who testified in the case, "a walking time bomb."

In what veterans' rights leaders say is the first major criminal exoneration linked to post-traumatic stress disorder, a jury in Canyon City in October found Bratcher was legally insane when he shot Medina.

"I only know of one cure for the experiences from these wars," said sociologist William Brown, a former Army drill sergeant. "And that's a lobotomy."

Wars have always sent home haunted souls — their anger, nightmares and flashbacks known as shell shock, combat fatigue or, beginning with Vietnam, PTSD. But many trauma experts say Iraq and Afghanistan are producing a troubling hybrid of stress and traumatic brain injury because of the roadside bombs that have become part of warfare. And unlike their Vietnam predecessors, who would normally serve a single tour, today's soldiers are sometimes serving three or four combat deployments.

"We're getting ready to face an epidemic," said Floyd Meshad, president of the National Veterans Federation and author of a book on helping PTSD victims with what he said will be, for many of them, an inevitable trip through the criminal justice system.

Though a PTSD diagnosis has helped reduce prison terms for some defendants — and resulted in the acquittal this year of a former Army captain in California charged with robbery — Meshad said he knows of no case other than Bratcher's in which a veteran avoided a murder conviction.

"This is a major precedent," he said.

Under Oregon law, Bratcher could have been convicted on a reduced charge of first-degree manslaughter if jurors had found he was a sane person acting in the passion of the moment. Instead, they found him "guilty except insane" — a ruling that will allow him to receive psychological treatment instead of prison.

"You're going to hear a story that has all the elements of a Shakespearean tragedy," Grant County Public Defender Markku Sario had told the jury during opening statements in the tiny rural courthouse in Canyon City. "War, sex, madness, violence. ... And it ends as most Shakespearean tragedies do: Everybody loses."

Bratcher was born and raised in Prairie City, just east of John Day, on land that rolls off the timbered mountains of eastern Oregon. His father, a Mexican farm worker, left almost immediately. His mother wasn't up to raising him, so he lived with his grandfather, David Baughman, a logger and auto body mechanic.