(Covers information from the S.D. Perry novels)
William "Billy" Coen was a military criminal who escaped execution when his MP jeep was overturned by monsters outside Raccoon City. He helped keep S.T.A.R.S. officer Rebecca Chambers alive in the day before the Mansion Incident.
In 1997 Coen was a Lieutenant in the US Marine Corps. Sent to an African rainforest on a top-secret anti-guerrilla operation, the team suffered casualties from the environment. Finding the 'hideout' to be an ordinary village, the angered team leader had its people rounded up and shot; refusing to do such a thing, Billy was knocked unconscious. After the massacre was found out, the team used Billy as a scapegoat in retaliation for his refusal.