"Joker" has inspired waves of headlines over apprehensions that its depiction of a mentally ill assassin could incite violence, prompting movie theaters across the country to take extra security precautions. New York and Los Angeles police increased their presence around multiplexes, and exhibition owners outlawed costumes and face masks in some venues. The industry started to make some of these moves the 2012 mass shooting in Aurora, Colo., at a midnight screening of "The Dark Knight Rises" left 12 people dead and 70 injured. Members of families affected by the Aurora shooting had spoken against "Joker."