Shawn Cavin — who has served and protected the Manteca community for the past 21 years — is retiring as a Manteca Police officer.His most rcenet assignment has been as East Union High’s school resource officer. He has served under five police chiefs: Richard Gregson, who hired him in 1964; Charlie Halford, Dave Bricker, Nick Obligacion and Jodie Estarziau. He joined the Manteca Police Department after serving six years in the U.S. Army with the 11th Mountain Division out of Ft.