Trump's partisan comments received cheers or jeers from the crowd, an expression of political views in uniform that would typically result in a reprimand.
Director Christopher Wray said the FBI remains concerned about the potential for violence at protests and rallies in Washington and in state capitols around the country.
Retired Lt. Col. Larry Rendall Brock Jr. was arrested after being photographed on the Senate floor during the deadly riot wearing a helmet and heavy vest, and carrying plastic zip-tie handcuffs.
“Lol to anyone who’s possibly concerned about the picture of me going around ... Not like I did anything illegal,” the Guardsman said in a social media post.
“We are working with the Secret Service to determine which service members supporting the national special security event for the Inauguration require additional background screening,” an Army spokesperson said.