I am of the opinion that Robin Williams is a much bigger piece of this puzzle than we realize.
Could be wrong, of course.
Just think of all he was involved in and/or had access to.
Spielberg. Woody Allen. Disney. Comedy Store/Laurel Canyon. Charities.
He sent a bunch of letters before he died, but we don't know who all received them or what information they could have contained.
When does a bird sing?
I think Robin sang once he was free.