John Smith is a convicted killer serving a prison sentence in Ohio that could keep him behind bars for life for the 1970s death of first wife, Janice Hartman. Authorities did not charge him for that crime until 2000, and it followed a roughly 25-year span during which Hartman disappeared. Smith’s family found her remains in a box in their Ohio home years later, which was then discarded on an Indiana highway. And Smith married twice more on both coasts of the country. Whether a Mercer County jury hears any of that history is up to Judge Peter Warshaw, who is mulling a motion by prosecutors to i…