DEVELOPING: New IG report “...we found at least six attacks committed in the United States by individuals who the FBI had previously assessed or investigated...” including 2009 Fort Hood, 2013 Boston Marathon bombing, 2016 Pulse Nightclub
https://oig.justice.gov/reports/2020/a20030.pdf#page=2
Related:
IG report finds HVEs (Homegrown Violent Extremists) carried out 20+ attacks (since 9/11) in US, “some of which occurred after the FBI closed a counterterrorism investigation..FBI has not taken sufficient action to address weaknesses”