Yes it was one my favorite TV series with a great theme song "Runaway" . The plot was excellent and tightly scripted. I remember the show ran around midnite time from 12am to 1am at the time.
If not wrong, the last episode was Ray Luca and Mike Torello 同归于尽 from a falling plane.
Actor Danny Farina was a real Chicago cop and that brought great believability to his character.