F.B.I. Said to Have Singled Out Potential Assailant in Capitol Officer’s Death. Sicknick, Brian D (1978-2021), Storming of the US Capitol (Jan, 2021), United States Capitol Police, Attacks on Police, Federal Bureau of Investigation, Proud Boys, Right-Wing Extremism and Alt-Right, United States Politics and Government, Murders, Attempted Murders and Homicides