The gunman who killed 26 people at a Texas church shooting on Sunday had a history of disturbing behavior, according to criminal and U.S. military records, former classmates and a former girlfriend who accused him of harassing her.Devin Patrick Kelley, 26, was court-martialed in 2012 for assaulting his then-wife and child, confined for 12 months and then given a bad conduct discharge from the U.S.