Dad in Custody Battle Kills 6 Gunman flees with kids, kills himself By Mary Papenfuss, Newser Staff Posted Aug 30, 2010 4:16 AM CDT 24 comments Comments Brian Diez, 26, shot dead his former girlfriend, her new boyfriend and three of their friends before killing himself. (AP Photo/Lake Havasu City Police Department) (Newser) – An Arizona dad locked in a vicious custody battle with his former girlfriend over their two children burst into her new boyfriend's home and fatally shot the couple, along with three other friends who were celebrating the boyfriend's 24th birthday. After the shooting, Brian Diez grabbed his young kids and fled to his sister's home in California, where he shot himself. The children were uninjured. Deborah Langstaff, 23, had obtained a restraining order against Diez ordering him to stay away from her and their children after he slapped their infant son. "It is heinous," Lake Havasu City police Sgt. Joe Harrold told the Arizona Republic.