Article Photos: How can red flags be missed like Navy shooter's? 1/8

Bishops Gerald Seabrooks, right, and Willie Billips stand in front of the home of Cathleen Alexis, mother of Washington Navy Yard gunman Aaron Alexis, who made a statement at her home in New York's Brooklyn borough on Wednesday, Sept. 18, 2013. The bishops are part of a Brooklyn Clergy-NYPD Task Force. Cathleen Alexis said that she does not know why her son did what he did and she will never be able to ask him. Aaron Alexis opened fire Monday, killing 12 people, before he was killed in a shootout with police. (AP Photo/Seth Wenig)