I tried to ask a question about the two meanings of Konjunktive II with a modal verb, but chose a bad example which led the discussion astray. Let me try a better one here. Look at the English sentence
He could have been killed.
This can mean two things.
(1) He is now dead. He wasn't sick, and he likely didn't commit a suicide, so he was probably killed.
(2) He is now not dead. He was caught in a gunfight, and if a gunshot had hit him, he would have been killed.
How would one express these two meanings in German? Is it:
(1) Er kann/konnte getötet worden sein.
(2) Er hätte getötet werden können.