Washougal has accepted the resignation of a police officer who assaulted a mentally ill man, was fired and later ordered reinstated.Robert. E. Ritchie, 54, of Washougal submitted his resignation effective this month.He was fired from the force in September 2012 for violating the police department’s use-of-force policy when he repeatedly punched Tyler Lampman, then 26, after Lampman spat on him. Lampman, who was mentally ill, was restrained and seated in the back of a patrol car when the assault occurred.Ritchie appealed his dismissal, and arbitrator Ronald L. Miller later ordered that Ritchie be reinstated to the police department. Miller concluded that the termination was too harsh a punishment for Ritchie, given the officer’s many years of service with the department. The city unsuccessfully appealed the decision.Ritchie returned to his job at the police department a couple of months ago. On April 24, he tendered his resignation, effective May 5.“After working 32 years in police work, I find it has come time for me to leave this chapter in my life and move on to another chapter,” Ritchie wrote.Washougal Police Chief Ron Mitchell said Monday that Ritchie was not asked to resign, nor offered any compensation for doing so.“He left on his own free will,” Mitchell said.Ritchie apparently has been working a second job. He was not immediately available for comment today because he was at work, his wife said by phone.Lampman, who has schizophrenia, was arrested July 1, 2012, on suspicion of domestic violence against his mother and brother. His mother said he hadn’t been taking his medications.