An Oelwein man accused of murdering his girlfriend is facing a hearing to determine if he’s mentally competent to stand trial. 40-year-old Tonie Barrett is charged with first-degree murder in the May killing of 28-year-old Marie Ferrell of Oelwein. Ferrell had been missing for several weeks before her body was found in June, buried in a shallow grave in Waterloo. Barrett’s attorney indicated last month that he would use the defense of insanity and diminished responsibility in the case. Based on a psychiatric examination, the judge scheduled a competency hearing for Barrett for October 31st at the Fayette County Courthouse. Barrett will also undergo a psychiatric evaluation at the request of prosecutors. Barrett allegedly killed Ferrell by choking her and stricking her in the head.