Buffy Goes to Washington by STFarnham & Lancer47 (I think.) Buffy gets interrogated by Gibbs for killing an officer, who's body happens to be missing even though both Gibbs and DiNozzo happen to witness the event.
Decided to check out Fanfiction.net to see if there was any good Buffy crossovers. I opened a bunch, but this was the only one I managed to read (it was the early morning and I really needed to sleep.) I enjoyed it, though I feel some things with the characters may have been a bit off. The ending was kind of amusing though.