Born and raised in Harvardville, Curtis lost his family in the Raccoon City Destruction Incident. He was once a part of the company WilPharma, but was fired/left after a feud with his superiors. He eventually joined the bioterror relief group Terrasave to protest against WilPharma but Terrasave disassociated themselves due to the violent threats Curtis made to WilPharma. He was used by the company as a scapegoat to hide the real dealers with the bioterrorists - themselves.
While he was inside the WilPharma research lab, a bomb was set off which caused heavy damage to the building. The G-virus (most likely provided by WilPharma researcher Frederic Downing) had infected Curtis then aided by his younger sister Angela. He transformed in front of her and defended himself against a heavily-armed Marine task force. He then turned on his sister to use her for breeding. Angela was saved by Leon S. Kennedy when he crushed Curtis with tons of metal schaffling. Soon enough, he began to mutate again. Becoming even more grotesque than before, he attacked the surviving Marines who were trying to escape in an elevator, tearing the elevator from its tunnel and hurtling it to the ground far below, killing all inside. He then turned to attack Leon and Angela once again.
DeathEditLeon and Angela managed to avoid Curtis for a short period of time, but he caught up with them and knocked Leon away while he chased Angela. He managed to regain consciousness for a brief moment when he picks up a picture of his family that Angela accidentally dropped from her pocket and tells Angela to escape.
As he lost his humanity again, he prepared to attack when suddenly the section he was standing on collapsed and he began to fall a great height. As he began to fall, he used the tail his mutation produced during his second transformation and wrapped it around Angela's foot while she was being held onto by Leon. As Angela pleaded Leon to let her go, he refused and instead shot Curtis in his skull, causing him to release his sister and careen downwards, dying on impact along with the explosion that followed.