My father CTB. I was told that no one knew why; no note, out of the blue. But that turned out to be a lie. Not only was it not out of the blue, but he had reached out days before to my grandmother, saying he was going to do it. Apparently she didn't tell my mom until recently (that he had told her that, but I suspect she knew, anyway). But he was also talking about it to other people, as well, and got no help.