(Portland, OR)  --  Multnomah County Sheriff's deputies are calling off the search for a missing inmate after finding him hiding in a ceiling air vent.  The Sheriff's Office says 29-year-old Robert Arrington was reported missing yesterday during a routine check at Multnomah County Inverness Jail in Northeast Portland.  Deputies placed the jail on lockdown while they searched for him.  They found him hiding about three hours later.  He's now facing additional criminal charges.