http://www.cnn.com/2005/US/05/04/til....ap/index.html

So, given that
... troops on the scene said they were immediately sure Tillman was killed by a barrage of American bullets.

The documents show that officers erroneously reported that Tillman was killed by enemy fire, destroyed critical evidence and initially concealed the truth from his brother, also an Army Ranger, who was near the attack...
then when the Army says "no systemic problems at Abu Ghraib -- senior officers not to blame", is that credible? Wouldn't it be like Enron investigating themselves?