Gunman Omar Mateen was active on Facebook before and during his rampage at a gay nightclub in Orlando, and he published several posts raging against the "filthy ways of the West" and blaming the United States for the deaths of "innocent women and children" abroad, according to a letter released Wednesday by the Senate Homeland Security Committee.
Mateen also reportedly pledged his allegiance on Facebook to the leader of the Islamic State, and commanded the US and Russia to stop bombing the militant group in the Middle East.
"America and Russia stop bombing the Islamic state..I pledge my alliance to [Islamic State leader] abu bakr al Baghdadi ..may Allah accept me," Mateen reportedly wrote in one post.
Facebook also provided the Senate committee with information showing that Mateen searched "Pulse Orlando" and "shooting" during the attack, leading to speculation that he might have been trying to see if his killing spree was trending on social media.
The letter from Senator Ron Johnson, a Republican from Wisconsin, requested Facebook's assistance in investigating Mateen's motives for the massacre, which left the 29-year-old Mateen and 49 other people dead. Speculation about why he attacked the nightclub initially focused on his apparent Islamic radicalism, but his ex-wife and a former classmate have since suggested that Mateen himself may have been gay. He reportedly frequented the nightclub in the past and had a profile on a gay dating app.
In his Facebook posts, Mateen reportedly said that America will "taste Islamic State vengeance" for the deaths of innocent women and children killed in airstrikes. He also vowed that there will be more IS attacks on American soil in the coming days, and looked for a speech by Baghdadi earlier in the week.
FBI director James Comey said earlier this week that there are no signs that Mateen was directly tied to any IS network, and that he was most likely just inspired by the group's propaganda.
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