Omar Mateen gunned down 49 people at the Pulse gay nightclub on June 12, 2016, in the deadliest mass shooting in US history. Photograph: (Getty)
Media reports have said that his wife Noor Salman may have had prior knowledge of his plan to carry out the massacre
The Federal Bureau of Investigation arrested the wife of Orlando nightclub shooter Omar Mateen at her home in California, a law enforcement official said.
Noor Salman was held on suspicions that she knew about her husband's plans to carry out the attack. He declined to provide further details of the arrest, but said she faced unspecified charges out of Florida.
Salman, who is of Palestinian descent, was taken into custory early on Monday, FBI spokesman Prentice Danner told AFP.
"This is a matter that we continue to take very seriously," US attorney general Loretta Lynch said on MSNBC.
"We said from the beginning we were going to look at every aspect of this case, every aspect of this shooter's life -- to determine not just why did he take these actions, but who else knew about them, was anyone else involved, is there any other accountability that needs to be had here in this case."
Mateen opened fire at the Pulse gay nightclub on June 12, 2016 killing 49 people in one of the deadliest mass shooting in US history.
Authorities said Mateen had become radicalised after watching online propaganda.
Media reported that Salman had called her husband after the news of the shooting broke. He texted her later asking if she had seen the news.
Salman is reported to have responded," I love you'.
(With inputs from AFP)