just 16 days after he had walked out of Southern Michigan Prison after serving the maximum of a six-year term, 20-year-old Dominick Piccone, was back again Thursday to start serving a life sentence for the murder of Romaine C. Potter and Cassius E. Barber, Oakland county farmers. During his wild flight, Piccone also killed Carl MacKenzie, a Jackson county farmer. A murder warrant cover ing that case was issued Friday to be placed on file at the prison. Piccone is pictured above with Warden Harry Jackson, right, after his arrival at the institution.