www.washingtonpost.com/nation/2021/02/09/capitol-riot-oath-keeper-fbi/
"The feds say he’s an extremist leader who directed rioters. He also had top-secret clearance and worked for the FBI, attorney says."
"Navy veteran Thomas Edward Caldwell led a band of the Oath Keepers extremist group to D.C. on Jan. 6 to storm the U.S. Capitol building, federal prosecutors allege, helping to mastermind a violent plot to stop lawmakers from certifying President Biden’s victory."
"But Caldwell’s attorney, Thomas K. Plofchan, says he isn’t just a retired lieutenant commander. Caldwell also had top-secret security clearance and served as a section chief for the FBI after leaving the armed forces in 2009, according to Plofchan."
I'm sure there will be many others in active duty and possibly some in the Capitol Police as well. I haven't found any recent news of internal investigations apart from some suspended officers in the days after the Capitol invasion.