(Portland, OR)  --  The principal of a Portland elementary school is on paid leave, pending the investigation of a domestic violence case.  KATU-TV reports Kelly Elementary School principal Marti Diaz was arrested on October 30th on charges of fourth-degree assault and domestic violence.  Portland police say Diaz was booked into the Clackamas County Jail following the arrest.  The case remains under investigation, but the Clackamas County District Attorney's Office has declined to pursue charges.