The FBI acknowledges it failed to tracked down school shooter Nikolas Cruz after being tipped off to a threatening YouTube post, but that missed opportunity was not the only red flag missed.

Nancy Grace discusses the investigation into the massacre at Marjory Stoneman Douglas High School with experts, including Brian Levin, director of Center for the Study of Hate and Extremism at Cal State Univ. – San Bernardino, Rob Hessell, a security analyst and author of “Safe City: From Law Enforcement to Neighborhood Watches,” former DEA agent David Katz, forensics expert Joseph Scott Morgan, child welfare law specialist Ashley Willcott, New York psychologist Caryn Stark, and Crime Stories contributing reporter John Lemley.

FBI tipped off in January about Florida school shooter’s guns, ‘erratic behavior’, and ‘expressed desire to kill people’

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[Feature Photo: Nikolas Cruz/Police Handout]