owned, operated, or otherwise controlled by a non-government entity such as a private corporation, or [1][2]
a law enforcement agency whole primary function is to provide contract based security services to private entities in a manner similar to private security companies.
^TM Becker (1974), "The place of private police in society: An area of research for the Social Sciences", Social Problems, 21 (3): 438–453, doi:10.2307/799910, JSTOR799910