there is no doubt about it. >> well actually there's been plenty of doubt and plenty of theories. >> my sister was dead. and did a lot of things go through my mind? yes. >> secrets, both suspected and imagined. >> is it possible that other people know more than they're saying? yes. >> it's certainly possible. beyond that, it's hard to say for sure. especially when it seems everyone has a story to tell. and those stories lead to accusations, often with zero proof. >> people are gonna believe what they wanna believe with no evidence. >> paradise valley arizona was home for the shacknai family, but the summers they spent in coronado were special, for dina and her son max. >> max loves the beach, he loved the water. he used to tell me on the way to coronado, mommy this is our place. >> she and maxes father jonah met in 1997.