Photo: AP

According to a letter released by the Senate Homeland Security Committee, Omar Mateen checked his phone to see whether “Pulse Orlando” and “shooting” had begun trending on Facebook after he took hostages during his deadly rampage at the gay nightclub on Sunday.

Investigators have identified at least five Facebook accounts thought to be associated with Mateen, 29. On one of them, he posted, “America and Russia stop bombing the Islamic state..I pledge my alliance to [its leader] abu bakr al Baghdadi..may Allah accept me.” Later, he wrote: The real muslims will never accept the filthy ways of the west” and “You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance.”

CIA chief John Brennan testified before the Senate Intelligence Committee on Thursday that the agency has not been “able to uncover any link” between ISIS and Mateen.

The letter, from Homeland Security chairman Ron Johnson, was addressed to Facebook CEO Mark Zuckerberg. “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. (Abu Bakr al-Baghdadi is the leader of the Islamic State.) “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’s letter did not explain how his staff had acquired this information. It did, however, ask Zuckerberg for his help with the committee’s investigation.

Here is the text of the letter:

June 15, 2016

Mr. Mark Zuckerberg

Founder, Chairman, and Chief Executive Officer

Facebook, Inc.

1601 Willow Road

Menlo Park, CA 94025

Dear Mr. Zuckerberg:

The Committee on Homeland Security and Governmental Affairs is examining the June 12, 2016 terrorist attack in Orlando, Florida. It is my understanding that Omar Mateen used Facebook before and during the attack to search for and post terrorism-related content. I appreciate Facebook’s support of the law-enforcement investigation into this attack and previous attacks. While Facebook is not a target of the Committee’s inquiry, I respectfully request your assistance with the Committee’s inquiry.

According to information obtained by my staff, five Facebook accounts were apparently associated with Omar Mateen. On June 12, 2016, Mateen apparently searched for “Pulse Orlando” and “Shooting.” Mateen also apparently posted “America and Russia stop bombing the Islamic state..I pledge my alliance to abu bakr al Baghdadi..may Allah accept me.” He then posted “The real muslims will never accept the filthy ways of the west” and “You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance.” In a final post, Mateen apparently wrote, “In the next few days you will see attacks from the Islamic state in the usa.”

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.” 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.

As the Committee examines the attack and considers legislative proposals to address homegrown extremism, I respectfully request your assistance with the Committee’s inquiry given Mr. Mateen’s use of Facebook. I ask that you please provide all Facebook 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. In addition, I request that appropriate company staff arrange a briefing with Committee staff on the information available to Facebook prior to and during this terrorist attack. Please provide this briefing and material as soon as possible but no later than 5:00 p.m. on June 29, 2016. When delivering production sets, please produce to Majority staff in room 340 of the Dirksen Senate Office Building and to Minority staff in room 613 of the Hart Senate Office Building.

The Committee on Homeland Security and Governmental Affairs is authorized by Rule XXV of the Standing Rules of the Senate to investigate “the efficiency, economy, and effectiveness of all agencies and departments of Government.” Additionally, S. Res. 73 (114th Congress) authorizes the Committee to examine “the efficiency and economy of operations of all branches and functions of the Government with particular reference to (i) the effectiveness of present national security methods, staffing and processes….” For purposes of this request, please refer to the definitions and instructions in the enclosure.

Sincerely,

Ron Johnson

Chairman