Washington ? Pat Tillman, the former pro football player, was killed by other American troops in a friendly fire episode in Afghanistan last month instead of by enemy bullets, according to a U.S. investigation of the incident.

New details released Saturday about Tillman’s death indicate that he was gunned down by members of his elite Army Ranger platoon who mistakenly shot in his direction during an enemy ambush. According to a summary of the Army investigation, a Ranger squad leader mistook an allied Afghan Militia Force soldier standing near Tillman as the enemy, and he and other U.S. soldiers opened fire, killing both men.

That Tillman, 27, wasn’t killed by enemy fire in a heroic rescue attempt was a major revelation by the U.S. military more than a month after the April 22 incident, which the Pentagon and members of Congress had hailed as an example of combat bravery. Tillman’s sacrifice of millions of dollars to become a soldier has been held up as a stark contrast to the prison scandal in Iraq.

Shortly after his death, Army officials awarded Tillman a Silver Star for combat valor and a Purple Heart. They said Tillman, a corporal, was killed while charging at the enemy up a hill, allowing the rest of his platoon to escape alive.

Instead, it appears Tillman’s bravery in battle led him to become a victim of a series of mishaps as he was trying to protect part of his stranded platoon, which Army officials say was attacked while hampered by a disabled vehicle it had in tow. The report said Tillman got out of his vehicle and shot at the enemy during a 20-minute firefight before he was killed when members of his unit opened fire after returning to the scene to help.

A woman who answered the door at the home of Tillman’s parents in San Jose said the family did not have anything to say publicly.

News of Tillman’s death by friendly fire was first reported Saturday in The Arizona Republic and the Argus of Fremont (Calif.) newspapers. New details about the incident emerged Saturday.

Military officials could not explain the discrepancy between earlier reports and the releases Saturday, saying that a monthlong investigation into the attack helped clarify the events. The investigation reports that Tillman was killed after he got out of his vehicle and fought about a dozen enemy insurgents in restricted terrain and in poor light conditions.

“While there was no one specific finding of fault, the investigation results indicate that Corporal Tillman probably died as a result of friendly fire while his unit was engaged in combat with enemy forces,” said Lt. Gen. Philip R. Kensinger Jr., who is in charge of the U.S. Army’s Special Operations Command, based in Fort Bragg, N.C.

Two other U.S. soldiers were injured by friendly fire in the same melee, though Army officials said Saturday they could not provide details. The full investigative report has yet to be released.

Tillman, an Arizona Cardinals safety, walked away from a $3.6 million contract and made less than $20,000 in the Army.