The F.B.I. is investigating 37 people related to the killing of Officer Brian Sicknick, the Capitol Police officer who died after being injured during the pro-Trump riot on Jan. 6, according to an F.B.I. memo sent to the private sector and others on Friday. The Times obtained a copy of the report.
Mr. Sicknick was struck with a fire extinguisher as a violent mob flooded the halls of Congress, according to two law enforcement officials. Lawmakers hid under their desks from violent protesters after President Trump encouraged them during a rally to head to the Capitol. Mr. Sicknick died in the hospital where he was getting treatment for his injuries.
Fourteen other Capitol Police officers were injured in the mob last week, the memo said.
Law enforcement officials are bracing for more unrest in the days leading up to the inauguration.
Since the Jan. 6 siege, intelligence officials have seen Chinese, Iranian and Russian efforts to fan the violent rhetoric, according to a joint threat assessment dated Thursday. The amplification is consistent with previous efforts to take advantage of divisive Republican rhetoric, such as the Russian efforts to amplify disinformation spread by Mr. Trump during the campaign about the security of mail-in voting.
The inspectors general for several federal agencies, including the departments of Justice and Homeland Security, announced on Friday that they had opened an investigation into the response to the riot at the Capitol. The watchdogs will also look at how federal agencies shared intelligence ahead of the riot.
Zolan Kanno-Youngs and Julian E. Barnes contributed reporting.
