NEW : Mexican authorities say they are investigating . Nancy Davis was shot by gunmen in a black pickup , police say . The FBI says it is looking into the shooting and has asked for help from local law enforcement agencies. `` They breathed Mexico . ( CNN ) -- That 's their love , '' friend said of the couple .
NEW : Mexican authorities say they are investigating . Nancy Davis was shot by gunmen in a black pickup , police say . The FBI says it is looking into the shooting and has asked for help from local law enforcement agencies. `` They breathed Mexico . That 's their love , '' friend said of the couple .