Homicide: Life on the Street, Season 4

Bayliss:
I didn't avenge Adena Watson's death. Now I never will. Never gonna know who killed her. I let her down, Gee.

Giardello:
You're gonna hafta make your peace with that.

Bayliss:
Let me ask you something, Gee. How do you know when to stop caring?

Giardello:
I've been a cop a long time. I can tell you how to sweet talk a confession out of a stone cold killer, sidestep the politics of me and the bosses. I can tell you how to work a case until there's nothing left to be done but to file the paperwork. But the one thing I can't tell you, is when to stop caring.