Police probe for info on gunman's mental health after Manhattan office shooting spree
                                
                                
                                    (Newser) -
                                    The man behind Monday's  deadly Midtown Manhattan shooting  bought his AR-15-style rifle from his boss at a Las Vegas casino, New York police officials revealed on Wednesday. Shane Devon Tamura, 27, paid $1,400 for the weapon, but authorities haven't disclosed if the transaction was illegal, per...