U.S. investigators say that the wife of the man who carried out the biggest mass shooting in U.S. history had some knowledge of his plans and had accompanied him on a "reconnaissance" mission to the gay nightclub in Orlando, Florida where the attack occurred.
Federal Bureau of Investigation officials say that Noor Zahi Salman, the 30-year-old second wife of the shooter, Omar Siddiqui Mateen, and the mother of their 3-year-old son, has been cooperating with their probe and could provide important information about why Mateen killed 49 people and wounded another 53 in three hours of mayhem early Sunday at the Pulse nightclub.
Salman has not been charged in the attack, but could face charges that she did not alert authorities ahead of time. Law enforcement officials are telling U.S. news outlets that she warned her husband not to carry out the attack as he left home for Orlando Saturday night.
One investigator said the couple visited the club between June 5 and 9. Authorities say the 29-year-old Mateen legally bought the weapons he used in the attack earlier in the month, including a semi-automatic assault rifle he used to fire a huge number of rounds at the late-night revelers dancing to Latin music. Heavily armed police killed him in a shootout after knocking holes into the club in a raid.
Angus King, a member of the Senate Intelligence Committee that was briefed on the investigation, told CNN, "It appears [Salman] had some knowledge of what was going on. She definitely is, I guess you would say, a person of interest right now and appears to be cooperating and can provide us with some important information."
U.S. Vice President Joe Biden says the Orlando shooting is "becoming clearer and more straightforward" as investigators try to determine the motive.
Biden did not elaborate Tuesday, but said that in the coming days President Barack Obama would say more. Obama is due to visit Orlando on Thursday.
The president, in comments Tuesday, said the shooting was carried out by an "angry, disturbed, unstable young man who became radicalized." He said there was no indication that any foreign terrorist group directed Mateen.
Mateen called Orlando's 911 emergency line three times as he carried out the attack, professing his allegiance to Islamic State leader Abu Bakr al-Baghdadi, and referencing the 2013 Boston Marathon bombing that killed three people.
Obama said U.S. law enforcement officials "are doing everything to stop these kinds of attacks," but are "sobered" by the difficulty in trying to detect "these lone actors" beforehand.
Obama, who has unsuccessfully sought enactment of tighter U.S. gun control measures, again called on Congress to limit the sale of high-powered weapons, such as the one Mateen used in the massacre. Other mass killers in the U.S. have used the same weapon, an AR-15, or a version of it.
The AR-15 allows shooters to fire many rounds as fast as they can pull the trigger. The AR-15 was prohibited for sale in the United States in 1994, but the ban was lifted in 2004 and has not been renewed.
Patrons at the Pulse nightclub said they had frequently seen Mateen there over the past several years. Others said they encountered Mateen, twice married, once divorced, on the gay chat and dating app "Jack'd."
One man, Ty Smith, said he remembered seeing Mateen at Pulse at least a dozen times.
"Sometimes he would go over in the corner and sit and drink by himself, and other times he would get so drunk he was loud and belligerent," Smith said.
Another man, Jim Van Horn, 71, said Mateen was a "regular" at Pulse. "He was trying to pick up people. Men," Van Horn told the Associated Press. Van Horn and others familiar with the gay club scene in Orlando say that Mateen may have been conflicted about his sexuality and acted out of anti-gay hatred in carrying out the rampage.
Mateen's father, Seddique Mateen, has told reporters his son became visibly upset after seeing two men kissing on a recent visit to Miami, in southern Florida.
Law enforcement authorities say that twice in recent years, they investigated Mateen's connections with terrorist groups, but concluded no charges were warranted and dropped further inquiries.
Now, the FBI, the country's top law enforcement agency, is taking a look back to see if signs of Mateen's radicalization were missed, even as it collects volumes of information about his recent activities leading up to his assault on the club.