DETROIT -- The gun used in the shooting of four Detroit Police officers on Sunday was traced back to an ex-convict.  Investigators say the 20-gauge shotgun used by Lamar Moore was purchased by Elijah Gayden last year.  It’s not known how Moore obtained the weapon.  Gayden was convicted of drug charges in Indiana in 1995 and spent time in prison.  He was in court for a preliminary hearing Tuesday and is scheduled to be back in court on February 9th.