Confronted by the sight of "Mother" standing over Dr. Raymond's bloody corpse, Norman's sanity finally snaps and he advances upon Mary, babbling. Mary backs into the fruit cellar and stumbles upon Lila's body, buried in a pile of coal. Assuming Norman is responsible, Mary raises her knife to kill him but is shot dead by the incoming police. The ensuing investigation is inconclusive, but in light of an overheard argument between Mary and Lila, Mary's attempt to kill Norman, and her dressing as his mother, the police determine Mary most likely committed all the murders.