The origins of the Grave Diggers lie with the excessive research and dumping of t-Virus test subjects at NEST which, when too much for Incineration Disposal Plant P-12A to handle, led to the virus contaminating the nearby soil and infecting underground-dwelling organisms.[excerpt 1][excerpt 2] Former S.T.A.R.S. officer Jill Valentine encountered a white Grave Digger when the ground subsided and found herself in the sewers it was burrowing through. Later, she encountered a brown Grave Digger in Raccoon Park. Desperate for a supply of food, it had smelt out a buried corpses and some zombies buried alive in the park's cemetery. Its attempt to burrow under each coffin led to the ground collapsing. This Grave Digger was killed by Jill.