Who is Levi Freemantle from The Last Child and what is their importance?

Levi Freemantle, a former prison inmate, is described as a slow-witted misfit, who talks and listens to God continuously. At one point, he is believed to be the killer responsible for the deaths of the abducted children. Freemantle, however, displays no actual violence, and his police "rap sheet" consists of relatively minor offenses.