A U.S. senator from Wisconsin revealed that Omar Mateen made several Facebook posts after carrying out Sunday's massacre at a gay club in Orlando – and is now looking for Mark Zuckerberg's help in the investigation.
Sen. Ron Johnson wrote to the Facebook creator in the wake of the mass shooting that left 49 dead and 53 wounded.
Johnson's staff uncovered evidence that links Mateen to five Facebook accounts active around the time of the shooting.
Mateen's social media accounts were taken down before they could be widely viewed by the public, but Johnson says his staff tracked down some or all of his posts – which were published during an hourslong standoff with police between the initial shootings and Mateen's death.
A look at some of the posts
The letter sent to Zuckerberg, which you can read here, claims Mateen posted: "America and Russia stop bombing the Islamic state..I pledge my alliance to abu bakr al Baghdadi..may Allah accept me."
Another: "You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance."
And, in his final post: "In the next few days you will see attacks from the Islamic state in the usa."
Mateen also searched for "Pulse Orlando" and "shooting" during the standoff, and a month earlier used Facebook to search for information on the San Bernardino killings.
The New York Times reports Mateen declared his support for the Islamic State in phone conversations with police during the three-hour standoff.
Facebook 'not a target' of probe
Johnson, chairman of the U.S. Senate Committee on Homeland Security and Governmental Affairs, writes that Facebook "is not a target" of the inquiry, but does "respectfully request" Zuckerberg's cooperation.
He is asking the social media giant for data on Mateen's activities, from both his and affiliated accounts, including activity logs, messages, photos, posts, and timeline information.
According to FOX News, Facebook has confirmed it has received the committee's request.
There were problems earlier this year when Apple fought the FBI's demands to turn over information from an iPhone belonging to one of the San Bernardino shooters.