If A has a camera and a roll of film and B buys the camera at a later date with a roll of film shot by A. B owns the camera, A, or his estate owns the copyright to the images. In the Maier case, Maloof bought a bunch of film, some processed some not, he sought out Vivian Maier's closest living relative and cut a deal. Some slimy sleaze ball lawyer (but I repeat myself) did a genealogy research after the images became famous and found another living relative with the same degree of consanguinity and cut a deal with Cousin #2 for a big piece of the action. I have not seen the decision, it was sealed, full non-disclosure, but here's how it probably played out: Maloof was screwed but still got a little, Cousin #1 was screwed but still got a little, Cousin #2 was screwed but still got a little, and the big winners were, brace yourself, the LAWYERS for both parties, especially the slimeball that brought the suit. Anytime something goes to court, the lawyers always win.
NB there is a class of lawyers that do intellectual property "prospecting" and are always filing patent infringement, trademark infringement, copyright, etc. suits. Occasionally they grab lapsed copyrights, abandoned intellectual property or buy up rights to old works, and then make out like bandits in the courts. There needs to be a revision of intellectual property rights to protect against these predators.