Omar Mateen,lucah main dalam keretaarina razif the gunman who murdered 49 people at a gay nightclub in Orlando on Sunday, posted on Facebook several times during the massacre. 

Mateen used five accounts to post various messages, according to a letter sent by Senate Committee on Homeland Security and Governmental Affairs Chairman Ron Johnson to Facebook CEO Mark Zuckerberg on Wednesday and published online. 

In his posts the gunman demanded an end to American and Russian airstrikes in Iraq and Syria, denounced the "filthy ways of the west," said that people would "taste the Islamic state vengeance," and wrote about more attacks in the coming days. 

Before he was shot and killed by law enforcement, Mateen also searched online for references to the massacre.

Johnson Facebook Letter

"In addition, my staff learned that in May 2016, Mateen used Facebook to search for information on the San Bernardino terrorists and on June 4, 2016, Mateen apparently searched 'Baghdadi Speech,'" Johnson wrote in the letter to Zuckerberg. "My staff has also learned that Mateen apparently used Facebook to conduct frequent local law enforcement and FBI searches, including searching for specific law enforcement offices."

Johnson asked Zuckerberg for his company's cooperation in providing "data on Mr. Mateen’s activities on his account and any affiliated Facebook accounts, including but not limited to activity logs, Facebook timeline information, Facebook messages, photos, and posts." He also requested "that appropriate company staff arrange a briefing with Committee staff on the information available to Facebook prior to and during this terrorist attack."

He asked Zuckerberg to do this by June 29.

The shooter pledged allegiance to ISIS a short time before he was killed. Despite this pledge, Mateen's radicalization came mostly by way of his own searches across the internet, according to intelligence officials. 

Though Mateen alluded to other shooters during the attack, there is no indication that he was working with a larger group.

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