"Police Quest is a series of computer games produced and published by Sierra On-Line between 1987 and 1993. The original series was composed of four adventure games, the first three of which were designed by former policeman Jim Walls, with the fourth title designed by former LAPD Chief Daryl F. Gates.
A spin-off from the Police Quest series, Daryl F. Gates' Police Quest: SWAT, was released in 1995 but was a FMV tactical simulator rather than a traditional graphic adventure. Although at the time it was considered Police Quest V and its sequel Police Quest VI. Both SWAT and the real-time strategy game SWAT 2 still carried the Police Quest name, although subsequent titles in the series would drop the Police Quest title."
Source: Wikipedia, "Police_Quest", available under the CC-BY-SA License.