A group of Dedham youths took community policing into their own hands late last month and reported a suspicious man at Greenlodge School. The youths told police that a man drove up to them while they were playing at the school June 22 and asked if they would dog-sit for him. The man, who was never located, then reportedly left the school only to return again with a similar request. It was then the group decided to call police, who responded shortly later but were unable to locate anyone who matched the description given.