I remember an old case where a family (about two guys and maybe two or three teenage boys) all vanished on a sailing trip. I've only seen the case once or twice, but I'd like to see it again. Does anyone remember this case? It's not the Cassie Nicole or the missing fishermen from Hawaii. I think this was more of a family vanishing and not so much mostly friends.

Sounds like the Liebling. Here's one of the threads:
http://www.sitcomsonline.com/boards/showthread.php?t=198996&highlight=Liebling

Yep, it's definitely the Liebling case. I don't think I've ever felt more sympathy for an UM interviewee as I did for Pamela Straight, the poor mother who lost all three of her children and her ex-husband (whom she still seemed to be on good terms with) in this tragedy. The most heartbreaking part is that she really didn't want her youngest son to go along and was SO close to asking him to stay home, but changed her mind when she saw how much he wanted to go.

Ah yes, the Liebling case. Truly a gut-wrenching story. I don't think it's really an unsolved nor mysterious one though--to me, all signs indicate that the boat simply sank. :(

The theory that Red Dixon kidnapped his sons and took them to Colombia just seems too far-fetched to me. First, had this been the plan he never would have taken along his friend, Mr. Georgen (can't remember the first name). Yes, I suppose he could have disposed of him via foul play, but most custodial kidnappers are NOT cold-blooded killers. Second, he and his ex-wife appeared to be on fairly good terms; the fact that she allowed all three sons to go fishing with him seems to indicate a high level of trust. Third, the oldest son was 18 years old, probably emancipation age and certainly past the age of parental brainwashing; you would think that he at least would try to make contact with his mother or friends back in California.

I agree wholeheartedly that Pamela Straight was one of the most tragic figures ever interviewed on UM. I don't have kids, but I can imagine that losing three children in one fell swoop must feel like having your heart ripped out. I'm amazed she was able to stay as composed as she did during the interview, and that she was able to participate in the re-enactment.