Sean Garrity. He has a wry and jaded disposition and is unsurprised at the ridiculous nature of the types of "crimes" he is called on to investigate. His first actual appearance was moonlighting as a Greendale campus security guard in the Season One episode "The Politics of Human Sexuality". His first appearance as a police officer was in "The Science of Illusion". He is portrayed by Craig Cackowski.
Cackowski was moonlighting as a security guard at Greendale when he caught Annie, Shirley and Britta trying to break into Dean Pelton's office ("The Politics of Human Sexuality"). He was next seen in his actual job as a police officer investigating what appeared to be a bizarre April Fool's joke on campus involving a cadaver from the science lab ("The Science of Illusion)". On Greendale's Family Day event he was called in to deal with the aftermath of a physical altercation between Ben Chang and Pierce Hawthorne over a misunderstanding of a Pictionary clue ("Basic Genealogy").
During the study group's second year together at Greendale, Cackowski's returned to deal with a mysterious Halloween party in the library ("Epidemiology"). He is later asked by his friend Professor Sean Garrity to help teach Dean Pelton, Jeff and Annie a lesson on the proper use of prop guns ("Conspiracy Theories and Interior Design").
In the study group's third year at school he is called to Troy and Abed's apartment for a breaking and entering incident there which saw Abed's prize special edition "Dark Knight' DVD having been stolen ("Foosball and Nocturnal Vigilantism"). Towards the end of the school year he retuns to the apartment with Abed who, along with the rest of the study group, had been expelled from Greendale and had been trespassing on school grounds ("Curriculum Unavailable"). He is called again to the apartment when the study group tries to convince him that Ben Chang had replaced Dean Pelton with an imposter. He is unbelieving of their claims and warns them to stay away from the school ("First Chang Dynasty").