US army officials withheld information about the death of NFL star turned soldier Pat Tillman, a US military investigation has reportedly found.
Tillman joined up six months after the 11 September terror attacks
Tillman died in Afghanistan in 2004 and for weeks afterwards US army officials said he was killed by enemy fire.
But army chiefs knew he had in fact been shot by fellow US troops, a report carried by the Washington Post says.
The truth about his death was concealed and evidence, such as his uniform, destroyed, the military report claimed.
Tillman turned his back on a contract with the Arizona Cardinals American football team, worth $3.6m (£2m), when he joined the US army six months after the 11 September 2001 terror attacks.
He enlisted in the US Rangers alongside his brother Kevin - a former professional baseball player with the Cleveland Indians - and both were subsequently despatched to Afghanistan as part of the US war on terror.
Fans flocked to pay tribute to the star when he died
Tillman died on 22 April 2004 when his US Rangers patrol was hit by gunfire as it passed along a canyon road in Khost province, south of Kabul at twilight.
The 27-year-old star was hit by a hail of bullets, which army officials quickly claimed came from the enemy - a story they stuck to for weeks afterwards.
However, The Washington Post, quoting the yet-to-be-released report, said that US army chiefs were informed that Tillman's death was the result of "friendly fire" within days of his death, but chose not to reveal this fact to his family or friends.
The true details of his death were not made known until 29 May 2004, weeks after a televised memorial service in which fans paid tribute to the man hailed as an "American hero".
According to The Washington Post, which first disclosed details of the 1,600-page report by Brig Gen Gary Jones of the Army Special Operations Command, Tillman's uniform and body armour were burned the day after he was fatally shot.
At the time, officials claimed his uniform had been burned because it presented a biohazard. However, investigators now say his clothes should have been preserved as evidence.
The new investigation was carried out at the request of Tillman family, who wanted to know why the uniform was burned and why information was withheld.
Gen Jones concluded there had been no official desire to hide the truth, the Washington Post said.
However, a US army spokesman admitted that there had been failings in what information had been passed on.
"Notifying families in a timely way that they have had a loved one killed or severely injured is complex and imperfect work. We can do better," he said.
The Jones report also described confusion among US troops when Tillman was shot, in which Tillman tried in vain to notify his fellow soldiers that he was not an enemy by waving his arms and throwing a smoke grenade.
The soldiers who shot him claimed that the poor light at sunset, when the incident occurred, had contributed to the error.