The FBI was too concerned about political correctness and did not launch an investigation into a man who was later charged with killing 13 people in a 2009 attack at the Fort Hood military installation in Texas, despite significant warning signs that he was an Islamic extremist bent on killing civilians, according to a lawmaker briefed on a new report about the terrorist attack.

In emails to a known terrorist, Army Maj. Nidal Hasan expressed his support for suicide bombings and killing civilians, while the terrorist, Anwar al-Awlaki, encouraged Hasan to stay in touch, Republican Rep. Michael McCaul, told The Associated Press on Wednesday after he was briefed on the findings of a new review of the attack.

The review was done by former FBI Director William Webster and was more than two years in the making. FBI Director Robert Mueller asked that Webster conduct an independent review, and the bureau is expected to release an unclassified version this week.

Much was already known about the series of oversights and missteps the government made leading to the terror attack at the Fort Hood Army post. Soon after the attack, it was revealed that members of two FBI anti-terrorism task forces saw emails between the Army psychiatrist and al-Awlaki beginning in December 2008. Those task forces reviewed the communications and decided they were in keeping with Hasan's research at the time, and as a result, no formal investigation of Hasan was opened. Hasan was writing a research paper about the effects of combat in Iraq and Afghanistan.

But McCaul said Webster's report offers some new details that show the FBI was concerned about investigating an American Muslim in the military, and that is why an investigation was not pursued.

The FBI in San Diego had been investigating al-Awlaki, a former San Diego resident, for his possible connections to the 9/11 hijackers. When agents saw emails between Hasan and al-Awlaki, they asked the FBI's Washington office to talk to Hasan's bosses, according to a government official briefed on the findings who spoke on condition of anonymity because he was not authorized to speak publicly about the Webster report. But the Washington agents thought that interviewing American Muslims who visit extremist websites was a sensitive issue and did not reach out to Hasan's bosses at the Defense Department, the official said.

"It shows you the length of the political correctness stuff going on," McCaul said after he was briefed on the findings of the independent review Wednesday.

Neither the FBI nor Webster responded to requests for comment. But the FBI and Defense Department have said that they've made several policy changes since the 2009 attack to help stave off similar attacks in the future.

One major change was that if al-Awlaki comes up as part of a terror investigation, FBI headquarters would be alerted, Mark Giuliano, assistant director for the FBI's National Security Branch, said last year.

Al-Awlaki, implicated in other terror plots, was killed in a drone strike in Yemen last fall.

Hasan, charged with killing 13 people and wounding 32 others in the November 2009 shooting rampage, is currently being tried in a military court.