Whenever people hear about a shooting in a school, workplace or anywhere, they usually assume the shooter is male.  But the shooting yesterday at You Tube headquarters stands out because the shooter was a woman.  We talk with a forensic psychiatrist about that... and with a security expert about the delicate balance between an open workplace and security.  Also on today's show... what special counsel Robert Mueller might do next... whether the U.S. is in a trade war with China... and a man who marched with Martin Luther King Jr. reflects on the death of the civil rights leader 50 years ago today.