The full Police Quest series:

Police Quest: In Pursuit of the Death Angel (1987)
Police Quest 2: The Vengeance (1988)
Police Quest 3: The Kindred (1991)
Police Quest: Daryl F. Gates' Open Season (1993)
Police Quest: SWAT

SWAT 2 and SWAT 3: Close Quarters Battle are sequels to Police Quest: SWAT, but they are not usually considered extensions of the Police Quest series.

The first four games can be found packaged together as The Police Quest Collection.