Updated 6:57 p.m. EST

The mystery over whether the military knew Fort Hood shooting suspect Nidal Hasan was communicating with a radical Muslim imam lapsed into finger-pointing ahead of congressional investigations looking into the Army psychiatrist's contacts with any extremists.

Even as President Barack Obama remembered those killed at the Texas Army post and condemned what he described as "the twisted logic that led to this tragedy," federal agencies reacted to conflicting claims about whether a Defense Department terrorism investigator looked into Hasan's contacts months ago with Anwar al-Awlaki. Awlaki, an imam who was released from a Yemeni jail last year, has used his personal Web site to encourage Muslims across the world to kill U.S. troops in Iraq. A military official Tuesday denied knowing Hasan had such contacts.

Two government officials, speaking on condition of anonymity because they were not authorized to discuss the case on the record, said the Washington-based joint terrorism task force