By Julia Edwards
WASHINGTON (Reuters) - The gunman responsible for killing 49 people at a Florida nightclub claimed a connection to or support for multiple Islamist extremist groups, including al-Qaeda, Hezbollah, al-Nusra and Islamic State, FBI Director James Comey told reporters on Monday.
He said a 2013 investigation into Omar Mateen began when he claimed a family connection to the militant groups al-Qaeda and Hezbollah and two Chechen brothers who killed three people with bombs at the 2013 Boston Marathon.
That investigation closed 10 months later when authorities determined the claims were made to "freak out" Mateen's co-workers.
Speaking to a 911 dispatcher during the siege at the Orlando, Florida, nightclub, Mateen expressed solidarity with an al-Nusra suicide bomber as well as the Islamic State.
Many of the groups are enemies, such as al-Nusra, an al-Qaeda offshoot at odds with the Islamic State.
"It's not entirely clear at this point just what terrorist group he aspired to support," Comey said at a news conference at FBI headquarters in Washington.
Mateen was dropped from an FBI watch list after the investigation, meaning he was able to buy firearms without the FBI being notified, Comey said.
"Hundreds and hundreds" of similar investigations are closed without charges or additional surveillance, Comey said.
Speaking along with Comey, U.S. Deputy Attorney General Sally Yates said authorities should take a "long and thoughtful look" at the policy regarding people previously under FBI investigation buying firearms. Currently, the FBI is not notified when someone formerly on terror watch list tries to buy a gun, Comey said.
Comey said that authorities know what kind of cell phone Mateen used but he declined to identify what type it was or whether the FBI has gained access to it.
Separately, a CBS News reporter said in a tweet that the shooter used a Samsung phone and that law enforcement had gotten into his computer.
There is no indication Mateen had any explosives, Comey said.
(Reporting by Julia Edwards; Writing by Susan Heavey; Editing by Leslie Adler and Bill Trott)