Who are the people trying to commit mass shootings, and how can they be stopped?

Dave talks with Garen Wintemute, the director of the Violence Prevention Research Program at UC Davis in Sacramento. Wintemute and his team, including Julia Schleimer, researched extreme risk protection orders (ERPOs), or "red flag laws" - a way for community members and family to alert local police to a would-be assailant's plans and disarm them. 

Their resulting study released just yesterday turned up a fascinating array of cases: including one in which the FBI worked with local police. Wintemute and Dave talk legality, and discuss the study's conclusion: that zero of the 21 cases where an ERPO was filed ended in a mass shooting.