Yes. Armstrong...
He faked a gunshot through the head. Then, pushed Dr. Armstrong off a cliff. (Wargrave was the killer)
He wanted to create the most unsolvable, greatest, mystery death that nobody could solve. He had been a judge for so long and he wanted to do something bad. He had a craving to kill, so he decided to...
Voldemort does end up dying at the hands of his own spell.
Some Atheists, some Agnostics can believe that once you are dead you are dead.