I'll raise my head above the parapet and risk being caught in the crossfire of multiple Musketry 😆, by saying that I'm inclined to agree with Michael regarding the MM and Saint Diana deaths. However, I have to disagree over Myra Hindley - her 'death' was very conveniently-timed indeed, and I've always strongly suspected that she was released very quietly, with a new identity, to spend whatever she had (has?) left of her life in anonymity.

But, in all three cases, I believe it's unlikely we will ever know the truth.