Abandoned Indiana Jones Mansion - Family Vanished Leaving Millions UNSOLVED CASE

Well, this is a strange explore, We're literally trying to piece the puzzle together on why this family disappeared leaving millions behind.
I mean look at this place! It's probably one of the most uniquely beautiful properties I've ever been to.
What gets me is the car..... Surely if they fled, they would have needed the car.

Has anyone got any theories?