Meet the man police say brought the world's biggest subway system to a screeching halt. Isaiah Thompson, 23, is suspected of pulling the emergency brakes on up to 40 trains in New York City, causing delays that cascaded through the subway system. According to authorities, the alleged culprit used the same M.O. every time, climbing into the last car through the rear door. Thompson allegedly had his own master key that he used to gain access to the train operator's cab, which is always empty.