REVERE – The arraignment of murder suspect Deshawn James Chappell was postponed on Thursday at Chelsea District Court due to a request for additional time by Bridgewater State Hospital for his competency evaluation.Chappell is charged with murder in the Jan. 20 slaying of 25-year-old Stephanie Moulton of Peabody at a North Suffolk Mental Health Association group home on Ocean Avenue in Revere. Prosecutors say Chappell killed Moulton, a counselor at the home, and later dumped her bloodied body behind St. George Greek Orthodox Church in Lynn.The next day, Chappell was ordered by Judge James H. Wexler to undergo an evaluation at Bridgewater. He remains held there without bail.Jake Wark, spokesman for Suffolk County District Attorney Daniel Conley, said he expects the 27-year-old former Chelsea resident’s arraignment to take place as soon as the next court date in about 40 days.”A defendant must be deemed competent to assist in his own defense in order to go to trial,” Wark said. “If he or she uses a criminal responsibility defense (insanity defense), it’s for the jury to determine whether the defendant was responsible for his actions at the time they were committed.”Wark stressed that while each case is unique, it’s possible that Chappell’s arraignment will drag on for some time due to his stay at Bridgewater. In some cases, Wark said years have passed before a decision was made.”We had a 2009 homicide trial for a case in which the defendant was charged and arraigned, but later deemed not competent to stand trial,” he said. “He was hospitalized for almost 10 years before his condition improved to the point where he was able to stand trial.”Forensic psychologist Dr. Naomi Leavitt previously mentioned in court that family members told her Chappell was a diagnosed schizophrenic who had been off his medication for some time.