Chattanooga Shooter's Motivation 'Unknown'

WASHINGTON — Investigators have found no information that alleged Chattanooga, Tennessee, shooter Mohammad Youssef Abdulazeez was "either inspired, directed, or assisted by individuals associated with an identified designated foreign terrorist organization," and his motivation "remains unknown," according to a bulletin sent to law enforcement agencies, sources tell ABC News.

The Joint Intelligence Bulletin, sent by the Department of Homeland Security and the FBI to 18,000 law enforcement agencies in the U.S. regarding the shootings at two military installations Thursday that left 5 dead, says state "the FBI investigation into his activities while overseas and the nature and extent of his affiliation with [foreign terrorist organizations] is ongoing."

The bulletin details the alleged assailant's citizenship and recent travels to Jordan, stating, "Abdulazeez, 24, a naturalized citizen with parents of Jordanian origin—became a US citizen in 2003 (derived citizenship) and previously traveled on at least four separate occasions to Jordan—with the last recorded date of travel between April and November 2014."

Authorities are looking closely at that recent trip, but the bulletin states, "We have no information to date to suggest that these trips were associated with any nefarious or violent extremist activities."

Sources stressed that the investigation is in its early stages. Communications devices related to Abdulazeez are being scoured and computer forensics are being conducted at the FBI lab at Quantico, Virginia as part of the search for answers. Law enforcement sources say the suspect is looking at this point like a classic lone wolf who operates under the radar of authorities.

The bulletin was sent to provide the latest guidance on the investigation to law enforcement officials around the country.

A full scale terrorism investigation using the FBI, local law enforcement, intelligence agencies and foreign allies is underway, trying to determine the motive behind the attack.

Senior government sources have told ABC News that the FBI and other agencies planned to interview family, friends and associates to assess Abdulazeez’s state of mind and any shifts in personality and behavior that may provide clues to why he wanted to kill members of the U.S. military.

They also are going to focus on these areas to ascertain motive:

—Abdulazeez’s overseas travel: Officials want to trace his travel and see whether he secretly went to other countries beyond Jordan. Authorities are asking foreign intelligence services whether Abdulazeez ever came up on their radar and whether there is any indication he ever met with or had interactions with ISIS or other terror groups.

—Abdulazeez’s computer and phone: The FBI will conduct forensic exams on Abdulazeez’s phones and computers. Those items were sent to the FBI lab in Quantico, Virginia today.

—Abdulazeez’s presence on social media: There will be an intense focus on Abdulazeez’s social media footprint and whether the suspect had been using aliases online in an attempt to mask his activity. FBI Director James Comey has said the ISIS social media campaign has been successful in recruiting here in the U.S.

“Americans all over the place responding to this constant push and feed and buzz. It’s the devil on your shoulder all day long saying kill, kill, kill,” Comey said.

Authorities will look for evidence that Abulazeez may have used encrypted communication to hide potential contact with radicals. This is a recent tactic used by ISIS that Comey expressed concern about last week.

FBI sources say they are concerned that they are looking at a “nightmare scenario,” a suspect who was not on their radar — not under investigation, not under surveillance — who shows up out of nowhere and goes on a killing spree. This comes as the FBI wrestles with trying to track hundreds of suspected ISIS sympathizers across all 50 states.

The Department of Homeland Security and the military are taking steps today to shore up security at federal buildings and recruiting centers across the nation, in an effort to prevent any "copycat" attacks.