Although the government uses TSDB as both an investigative database and an "early warning" tool, inclusion on the list does not invariably prevent attacks or threats. For example, in October 2011, the FBI added Tamerlan Tsarnaev's name to the TSDB, before Tsarnaev committed the Boston Marathon bombings in April 2013. Omar Mateen was on the TSDB for a period of time before he committed the Pulse nightclub massacre. Dozens of people listed in TSDB, mostly those flagged in connection with past concerning white supremacist connections, were present in Washington, D.C., during the January 6, 2021 attack on the Capitol building by a violent pro-Trump mob.