A newly released documentary reopens the case of Pat Tillman, the football star who left behind a lucrative NFL career after the 9/11 attacks to join the Army. The one-time Arizona Cardinals safety was killed in Afghanistan in an April 2004 incident that was initially represented by the Pentagon as an enemy ambush, but later revealed to be a friendly-fire incident. While the apparent cover-up around Tillman's death prompted a congressional investigation, no one in Washington or the Pentagon was ever censured. Now, The Tillman Story, a documentary by filmmaker Amir Bar-Lev, delves into the still-vexing questions around the star athlete's death. "Even if you know what happened in broad outline," says Kenneth Turan in the L.A. Times, "the specifics are shocking." (Watch The Tillman Story trailer.) Here are several key takeaways from the film:

Tillman was not the "meathead jock" you might expect
Tillman didn't fit the stereotype of an American football player, writes Turan. In Bar-Lev's film, he comes across as a "free-spirited iconoclast who effortlessly went his own way." An atheist, an academic, and a fan of linguist Noam Chomsky, Tillman was not, as a friend puts it in the movie, a typical "meathead jock."

The "kids" who killed Tillman were trigger-happy
The Army said the incident happened under the "fog of war," but this "devastating" documentary offers a more compelling explanation, writes Stephen Holden in The New York Times — namely, that the platoon-mates who killed Tillman were "itching for a firefight." Soldiers don't always begin shooting reluctantly, says Stan Goff, a former special ops officer quoted in the film. "It's an imposition of a level of wisdom and maturity on soldiers that doesn't apply to 19-year-olds anywhere, ever."

"I'm Pat f---ing Tillman"
A particularly harrowing moment is the film is the reconstruction of the final seconds of Tillman's life, says Richard Corliss in Time. A fellow soldier describes Tillman, injured by gunfire from an approaching group of Army Rangers, crying out "I'm Pat F---ing Tillman!" in the desperate hope his platoon-mates would recognize him and hold their fire. His call was in vain, as another volley of friendly fire left him dead.

Public tributes to Tillman worsened his parents' pain
Tillman's death provoked a "grand and glitzy public outpouring of grief," says Stephanie Zacharek at Movieline, that his parents found very difficult to reconcile with their own private suffering. Bar-Lev illustrates this in a shot during a memorial football game which shows "a team of prancing and high-kicking dancers" lining up on a football field in front of Tillman's family to the tune of Stars and Stripes Forever. "No satirist would have dared paint that picture," writes Corliss.

The military tried to cover up Tillman's death — and capitalize on it
The Pentagon tried to discourage the grieving family's efforts to investigate Pat's death, says The N.Y. Times' Holden. But the Tillmans' continued efforts "unearthed more and more disturbing facts, among them that the military had burned Pat’s uniform, body armor and diary." It turns out the cover-up went straight to the top, says Lisa Rose at the N.J. Star-Ledger. "Gen. Stanley McChrystal was instrumental in turning Tillman's death into a recruiting tool."

No specific villains, no final answers
Despite the troubling conduct by Gen. McChrystal and others, "Bar-Lev opted not to single out an individual but instead convey that everyone -- the military, the government and the public -- played a role in how his death was handled," says Rose. As the film explores how deep the cover-up goes, "all hope of clarity evaporates," says Bob Mondello at NPR.  Indeed, you "emerge from The Tillman Story feeling a little of what the Tillman family must: that the whole truth about his death hasn't yet been told, and may never be."