The Deepening Tragedy of the Maine Massacre

The national outcry after mass shootings always includes calls to keep guns away from dangerously troubled people. That possibility existed ahead of the devastating violence in Lewiston, Maine, as much as with any case in recent memory.

Army reservist Robert Card, the 40-year-old suicidal perpetrator who killed 18 people and injured 13 others at a bowling alley and a bar on October 25, displayed numerous warning signs far in advance. His erratic behavior going back months included complaints he was hearing voices, angry and paranoid claims about being smeared as...