Kauzlarich said he was confident the current probe would not result in criminal charges against the shooter or shooters.
He said investigators would not still be examining the killing if it were not for Tillman's NFL celebrity -- he walked away from a multimillion-dollar contract with the Arizona Cardinals when he enlisted -- and the pressure brought to bear by Tillman's family or a number of Washington politicos.
"His parents continue to ask for it to be looked at," Kauzlarich said. "And that is really their prerogative. And if they have the right backing, the right powerful people in our government to continue to let it happen, then that is the case."
"But there [have] been numerous unfortunate cases of fratricide, and the parents have basically said, 'OK, it was an unfortunate accident.' And they let it go. So this is -- I don't know, these people have a hard time letting it go. It may be because of their religious beliefs."
In a transcript of his interview with Brig. Gen. Gary Jones during a November 2004 investigation, Kauzlarich said he'd learned Kevin Tillman, Pat's brother and fellow Army Ranger who was a part of the battle the night Pat Tillman died, objected to the presence of a chaplain and the saying of prayers during a repatriation ceremony in Germany before his brother's body was returned to the United States.
Kauzlarich, now a battalion commanding officer at Fort Riley in Kansas, further suggested the Tillman family's unhappiness with the findings of past investigations might be because of the absence of a Christian faith in their lives.
In an interview with ESPN.com, Kauzlarich said: "When you die, I mean, there is supposedly a better life, right? Well, if you are an atheist and you don't believe in anything, if you die, what is there to go to? Nothing. You are worm dirt. So for their son to die for nothing, and now he is no more -- that is pretty hard to get your head around that. So I don't know how an atheist thinks. I can only imagine that that would be pretty tough."
Asked by ESPN.com whether the Tillmans' religious beliefs are a factor in the ongoing investigation, Kauzlarich said, "I think so. There is not a whole lot of trust in the system or faith in the system [by the Tillmans]. So that is my personal opinion, knowing what I know."
Asked what might finally placate the family, Kauzlarich said, "You know what? I don't think anything will make them happy, quite honestly. I don't know. Maybe they want to see somebody's head on a platter. But will that really make them happy? No, because they can't bring their son back."
Kauzlarich, now 40, was the Ranger regiment executive officer in Afghanistan, making him ultimately responsible for the conduct of the fateful operation in which Pat Tillman died. Kauzlarich later played a role in writing the recommendation for the posthumous Silver Star. And finally, with his fingerprints already all over many of the hot-button issues, including the question of who ordered the platoon to be split as it dragged a disabled Humvee through the mountains, Kauzlarich conducted the first official Army investigation into Tillman's death.
That investigation is among the inquiries that didn't satisfy the Tillman family.