Clad in a thin hooded sweatshirt, Terry Norton trembles uncontrollably behind the wheel of his beat up Chevy.<p/> His gas tank is empty, but he can't muster the strength to walk the two miles to buy fuel. With South Florida in the grip of a record-setting cold snap, he and other sex offenders and predators who live under the Julia Tuttle Causeway huddle in their cars, nylon tents and wooden shacks.