A former bus driver for the Scarborough school system has been charged with asking a 16-year-old girl to send him a nude picture of herself. Stephen Mitton of Westbrook was ordered held on $5,000 bail after appearing Wednesday in Cumberland County Unified Criminal Court on charges of sexual exploitation of a minor and unlawful sexual touching. The 47-year-old Mitton was also ordered to have no contact with the alleged victim or her mother. According to court documents, the alleged victim was the daughter of a friend, and the touching involved slapping her behind. Scarborough school officials say Mitton quit on Tuesday, and the charges do not involve Scarborough students. He had worked for the district for a year. Police say the alleged crimes occurred in Westbrook.