You know how one of the things about Gibbs is that he's been married a few times? Shannon was his first wife. She and their daughter were killed, I believe, around the time of the first Gulf War. There has only been sporadic mention of them over the seasons but more comes out each year. There was one episode a couple of years ago or so (I think after Ziva started but I don't remember for sure) that had to do with Gibb's daughters best friend. That one was kind of heart breaking. During the episode, it came out that the daughter and her friend had buried a treasure chest/time capsule in Gibb's back yard. The now grown friend told him about it and where to find it. He dug it up during the episode but never opened it and at the end, reburied it. If you went to the show's site at CBS.com, you could open it and see what was inside. (I think that may still be there, I don't know). It was kind of sad actually.