04/21/2014 at 02:10 PM EDT
For the last decade, Steven Elliott has struggled with the horrifying possibility that he fired the fatal shots that killed fellow Army Ranger Pat Tillman during the confusion of a firefight.
"It is possible, in my mind, that I hit him," Elliott, 33, told ESPN's Outside the Lines
in an interview that aired Sunday.
Tillman, a former NFL player for the Arizona Cardinals, was killed April 22, 2004, in the mountains of Afghanistan during a gun battle by what the military later determined to be friendly fire
Elliott, 33, who left the Army in 2007, says he has been treated for post-traumatic stress disorder and is now speaking out to help other veterans suffering the same problems.
Neither the Army nor the other shooters in the firefight commented to ESPN, nor did Tillman's family. The Army says Tillman was killed by three shots to the head but has not said where it believed those shots came from.
"You aim at a point, and you fire a burst," says Elliott. "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 has not spoken to Tillman's family, but has this message for them: "You just want to tell them how sorry you are and how completely inadequate those words feel."