The Paranormal Control & Investigation first appears in Slayer Advance Season 6 episode E84: Quick Sweep. In this episode the PCI, while not yet identified as such, deploys a special forces team called a Death Unit to kill demons and vampires in the Hudson Valley area. The PCI also appears without name in a few episodes in which Alexis is mysterious given the ability to become a police officer and later a United States Crisis Unit in Season 6's episode E86: Officer Perry. The Paranormal Control & Investigation later makes a full appearance in Slayer: Darkness Conspires in which Alexis is officially hired by the agency.
The Paranormal Control & Investigation, in Slayer, is a secret and classified government agency under the authority of the Department of Defense. Its primary purpose is to combat the forces of darkness nationwide and worldwide by deploying highly skilled and trained agents on missions. The PCI headquarters in located underneath the Pentagon in Arlington, Virginia. Alexis is hired as a special agent in Slayer DC Season 1 episode E1: Welcome To The PCI. She learns how the government and later the PCI have been monitoring the slayers and Alexis and have provided aid to allow Alexis to get where she is today.
The PCI agency and United States government have led to the inventions and advancements in combatting the forces of darkness by developing and perfecting electro-magnetic weapons, static weapons, hellfire ammunition, portal generators for travelling into other dimensions and later dimension destroying weapons for collapsing demon worlds.