Giles: Whatever the authorities have planned for her, it can’t be much worse than what she’s doing to herself. She’s taken a human life. The guilt, it-it’s, it’s pretty hard to bear, and it won’t go away soon.
Cordelia: I guess you should know, since you helped raise that demon that killed that guy that time?
Giles: Yes. Do let’s bring that up as often as possible.
Buffy the Vampire Slayer, Season 2: Episode 11 – “Ted”