(Portland, OR) -- A convicted sex offender charged with kidnapping, sexually assaulting and murdering an elderly woman is expected to undergo a mental health evaluation. A judge postponed arraignment proceedings for Timothy Mackley yesterday over questions of whether he is mentally fit to be prosecuted. Mackley says he suffers from schizophrenia and bipolar disorder. Police arrested him last week after finding a body inside his car during a traffic stop. That body turned out to be that of 89-year-old Marcine Herinck, whose disappearance for more than a week sparked a major search. Investigators believe Mackley followed Herinck home from a thrift store where she volunteered and kidnapped her.