The pair soon notices the same mysterious young man, moments before the train suddenly begins moving again. Unbeknownst to the pair, two soldiers from Umbrella, on the orders of Albert Wesker and William Birkin, attempt to take control of the train and destroy it, but are killed by leeches before they can complete their mission. As the train speeds out of control, Rebecca and Billy apply the brakes and avert its course towards an abandoned building. Upon exploring the area, they discover it to be a disused training facility for future executives of Umbrella, and that the former director of the facility and the corporation's co-founder, Dr. James Marcus, was responsible for discovering the so-called Progenitor virus in the 1960s, and decided to examine its potential as a biological weapon. He combined it with leech DNA to develop the T-virus that causes rapid mutations in living organisms and thus transforms humans and animals into zombies and monsters.