Pity Him Afterwards — Donald E. Westlake

Hiding in the darkness of the trees, he was waiting for the state police car to move on, but it would not. Red lights filled the road below, flashlights began to search the woods around him. But he would not go back to Doctor Chax. He could take no more shocks. No more dying, day after day, and coming to life in pain. Whatever it takes, he will be free.