When the player enters the Power Core Access area in Doom 3, a female voice can be heard crying. When the player reaches Theresa's office and enters it, she pleads for help before abruptly turning away with a demonic snarl. Before the player can do anything, however, a Lost Soul suddenly tears itself out of Theresa's head, ripping out her spinal cord, and attacks the player. Many more Lost Souls are encountered during the game, although this is the only time one is seen to originate from a living human. How exactly the Lost Soul got to be inside of her in the first place is not known.