The wife of Orlando gunman Omar Mateen may have known about his plans to carry out the fatal nightclub shooting, according to reports in United States media.
Mateen killed 49 people and injured 53 others when he opened fire at gay nightclub Pulse early on Sunday (local time) -- the worst mass shooting in modern US history.
According to NBC, officials familiar with the case said Mateen's wife, Noor Zahi Salman, told the FBI she was with him when he bought ammunition, and once drove him to the nightclub "because he wanted to scope it out".
Video from Florida TV station WSVN shows Ms Salman being escorted from her house by police. She is co-operating with authorities but is not in custody.
Noor Zahi Salman (L) and Omar Mateen (R)
Ms Salman told federal agents she tried to talk her husband out of carrying the attack, but authorities are now considering filing criminal charges against her for failing to warn them of his plans.
The New York Times also cited a senior law enforcement official saying the FBI is "trying to determine her level of involvement".
"There's an indication that she was with him in certain parts of the process," said the anonymous official. "We don't know what's true and what's not."
Mateen died at the nightclub in a shootout with police. The couple have a three-year-old son.