I have some shocking news, GMs. You are not Sir Arthur Conan Doyle, and your players are not Sherlock Holmes. So when you run a mystery, you should save yourself, and your players, the frustration of expecting your players to just, somehow “get it”. Yes, it’s great when someone puts 2 and 2 together (that’s 22, right?), but those moments are the exception rather than rule, and can only serve to highlight good mystery planning, rather than being relied upon to drive the plot forward.
This is for the simple reason that no one can see inside your head. GMs who are in all other cases highly descriptive when it comes to hack n’ slash dungeon crawls, will all too often suddenly expect players to read their minds when it comes to a horror/mystery like Call of Cthulhu. In order for players to put together the pieces of this intricate puzzle, you have to stop holding out on giving them the pieces.