In his first public statements about the death of Pat Tillman, the former NFL player turned Army Ranger, one of the fellow Rangers involved in the 2004 friendly-fire incident in Afghanistan told ESPN's "Outside the Lines" he has lived for 10 years with the thought that he might have fired the fatal shots.

"It is possible, in my mind, that I hit him," said Steven Elliott, who had been engaged in his first firefight as an Army Ranger when Tillman died on April 22, 2004, in the mountainous terrain of southeast Afghanistan.

The events leading up to one of the most infamous friendly-fire deaths in U.S. military history were rife for second-guessing from the start: After an Army Humvee broke down in the mountains, Tillman's platoon was ordered divided by superiors so that the Humvee could be removed; a local truck driver was hired as the hauler. But the two groups struggled to communicate with each other as they traversed the steep terrain. And the second group soon became caught in a deafening ambush, receiving fire as it maneuvered down a narrow, rocky canyon trail.

Tillman's group, which had traveled ahead, scaled a ridgeline to provide assistance to fellow Rangers under attack. But a squad leader, Sgt. Greg Baker, in Elliott's armored vehicle misidentified an allied Afghan soldier positioned next to Tillman as the enemy and opened fire, killing the Afghan and prompting Elliott and two other Rangers to fire upon what Elliott called shadowy images, later learned to have been Tillman and then-19-year-old Bryan O'Neal.

The Army either has never determined or has never released whose shots killed Tillman. Tillman had left the Arizona Cardinals after the Sept. 11 terrorist attacks to join the Army, a decision that immediately turned him into a national symbol of sacrifice.

Elliott, 33, who left the Army in 2007, has spoken at length with "Outside the Lines" in recent months. He said he has been treated for post-traumatic stress disorder and is speaking now because he believes that his story might provide hope for fellow veterans who suffer similar afflictions.

The other two shooters who have acknowledged firing at Tillman's position declined comment for this story, as they have in the past.

Investigations by the Army determined that Tillman died from three shots to his head. Elliott, whose weapon was an M240 Bravo machine gun, and platoon mate and Spc. Trevor Alders have been most widely suspected of having fired the fatal caliber of rounds, based on autopsies and Army investigations.

The locations of the fatal bullets, all in an approximately two-inch area of Tillman's head, could have been too neat and too precise to be the work of a machine gunner. But Elliott said he was trained to fire his automatic weapon with the precision of a rifle, not to spray fire in Rambo-like fashion.

"You aim at a point, and you fire a burst. You are holding your trigger for a fraction of a second, but that fraction of a second releases three to five rounds," he said. "If it looked like you had [three] rounds and very close to one another, well, that was very consistent to how I was firing my weapon at that point. ... It would be disingenuous for me to say there is no way my rounds didn't kill him, because my rounds very well could have."

Elliott's machine gun was normally equipped with a multipower scope for daytime, but the scope was broken and no replacement had yet to be found. As he took aim low on the ridgeline where Baker first engaged, he peered down the weapon's rudimentary, V-shaped iron sight. He said he remembers catching peripheral glimpses of the person he later learned was the allied Afghan soldier and of the shadowy figures -- presumably of Tillman and O'Neal -- silhouetted in front of rocks.

They were less than the distance of a football field away when Baker opened fire.

"The mantra is that when all else fails you do what your team leader does, you go where your team leader goes and you shoot where your team leader shoots, and so effectively ... " said Elliott, his chin quivering as he lifted his right hand to wipe away tears during an interview. "Effectively him firing at that position is, is the same as his giving an order to fire. ... And it breaks my heart to say that, because I know that he regrets that -- so much."

Baker, a respected platoon leader and the fittest of Rangers, previously acknowledged to "Outside the Lines" having mistakenly engaged the Afghan despite his wearing a desert camouflage uniform similar to what the Rangers wore rather than the tunic-and-baggy pants ensemble of Taliban and al-Qaida fighters. Baker acted upon seeing spitting muzzle flashes from the Afghan's AK-47 -- also the enemy's weapon of choice -- fired in the direction of his vehicle. But the Afghan, along with Tillman and O'Neal, actually were targeting an enemy position on the opposite hillside, O'Neal said.

Baker is out of the Army and lives in the Seattle area. Reached for comment on this story, he politely declined, saying, "I'm good, thanks."

O'Neal, a Ranger who survived dozens of large caliber rounds raking the hillside and kicking up the earth around him, remains in the Army. After another tour in Afghanistan in 2011-12, O'Neal said he still can't shake the high-definition images from a scene he was so sure he'd forget about.