A man on Maine’s sex offender registry for sexually assaulting a child is back behind bars for allegedly violating probation by approaching a 12-year-old girl outside a Richmond school. Authorities say 20-year-old Zachary Allen Dunning of Alna was arrested Friday. He was being held without bail Monday. Dunning was sentenced in February in Lincoln County Superior Court to five years in prison, with all but nine months suspended. He was released Aug. 4 and is on probation until at least August 2015. One condition of probation prohibits him from having contact with anyone younger than 16. Police tell the Kennebec Journal, that Dunning was arrested after he and a 17-year-old male companion had a conversation with two girls, ages 12 and 17 near a school. Neither girl was harmed.