I used to take each live packrat for a drive and then let it out of the trap about two miles away, but after a dozen such relocations realized it cost too much in time and gas. So, I devised a humane way to dispatch them, but it's not for everybody. I sleeve a Costco-size mesh onion sack over a big plastic bread bag to form a double, reinforced bag (the plastic bag alone isn't strong enough), and then slip the neck of the double bag over the end of the trap, keeping it tight so the rat can't squeeze out and escape. Then I open the door leading into the bag, and usually simply blowing at the rat once or twice makes it run into the bag. I gather the neck closed and remove the bag from the end of the trap; then, holding the bag securely by the neck I swing it (with rat inside), hard, in an arc against the concrete walkway. The rat dies instantly and is already in a plastic bag for disposal.