Seeking revenge for the destruction his South American home town, Santa Cabeza, Carlito and his younger sister Isabela Keyes infect the entire population of Willamette, Colorado turning the people into zombies.
He is a cruel and calculated individual who is focused only on gaining revenge on the American people. He is distrustful and will go to any lengths to ensure that his ideas go as planned. His hatred spurns on acts of terrorism, which are carried out to reveal the truth. His will, desire and strength are to be reckoned with.
He is experienced with firearms and explosives, and fights tenaciously against Brad Garrison and Frank West using a sniper rifle. As Carlito retreats, he is shot in the arm, and shoots Brad in the leg, leaving him seriously injured.
Frank, after confronting Isabela, gets her to try and convince Carlito to surrender, leading to a disastrous result. Carlito, now beginning to lose his very sanity, shoots Isabela, leaving her running back to Frank for help. Isabela, now on sides with Frank, Brad, and Jessie, tells them her and Carlito's backstory from Santa Cabeza, and that Dr. Barnaby, was the lead scientist at the American Livestock Research Facility, responsible for the Santa Cabeza outbreak. This finally reveals Carlito's motive, and his lust for revenge.
After being mortally wounded in the stomach by Brad, Carlito is dragged off by the insane Larry Chiang. Frank defeats the psychotic butcher and speaks to Carlito, who had been hanging on a meat hook. After Frank promises he will tell everyone the truth about Santa Cabeza, Carlito gives him a locket before he dies. The locket is for Isabela, and contains a password ("pachamama") for Carlito's laptop.