(CNN) The wife of Orlando nightclub shooter told the FBI that Omar Mir Seddique Mateen said he wanted to carry out a jihadist attack, though she denied knowledge of his plans to launch the deadliest mass shooting in U.S. history, a law enforcement official told CNN on Tuesday.
FBI investigators don't believe Noor Salman was a co-conspirator in the attack that killed 49 people Sunday morning at Pulse, the source said.
But authorities are looking into whether she should face charges for what she may have known of his intentions and possibly failed to report to law enforcement.
The development comes as investigators try to understand what motivated Mateen to carry out the devastating attack. Forty-nine people were killed early Sunday and 53 people were wounded. Officials said that 28 victims are still hospitalized, including at least four people who are in critical condition.
Salman, Mateen's second wife, has been cooperating with various law enforcement agencies. The couple has been married since 2011. They have a 3-year-old son.
The couple lived in Fort Pierce, Florida, about an hour from the club. Salman told the FBI she had noticed changes in her husband's behavior and tried to dissuade him from doing anything violent, the official said.
When he left their home Saturday, hours before the mass shooting, Mateen lied about where he was going, Salman told federal investigators.
A separate source told CNN that Salman had some prior knowledge of her husband's intention to launch an attack.
Law enforcement officials said Salman accompanied Mateen on trips to scout potential targets, though it is unclear how much she knew about his intentions. She was with him when he visited Pulse and Disney Springs -- an entertainment and shopping complex -- apparently in early June.
She also accompanied him on an April 26 visit to Disney World. Disney security officials have told the FBI that they believe the visit was to conduct reconnaissance.
The early June visits took place during the same period Mateen was purchasing the weapons used in the devastating attack.
Maine Sen. Angus King, who as a member of the Senate Intelligence Committee was briefed on the investigation, told CNN's Wolf Blitzer said he doesn't know whether Salman went with her husband to purchase the guns.
Hours before the carnage, Mateen made one last trip to Disney Springs, law enforcement officials said. That time, Mateen was alone.
Justice Department prosecutors and FBI investigators are reviewing Salman's account and other evidence to determine whether to bring charges against her for allegedly failing to report her knowledge of his general plans to carry out some kind of attack.
Such charges could include misprision, a deliberate concealment of knowledge of a pending crime.
King told Blitzer that Salman is being interviewed by the FBI.
"It appears she has some knowledge of what was going on, visiting some of the other sites. We don't know whether she was involved and knew about the purchase of the guns, which took place only about a week before the attack," King said. "But 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 on who this guy is, what his motivations were and what his plans were."