I think I'd approach this problem by giving the actors a Boolean flag using actor values. Initially, set the flag to True which would mean that the actor is live. When you want to remove the actor from the scene, set the flag to to False (not live), then kill it.
When the actor is killed, check the flag to see if the actor is live, and if it is, carry out the appropriate action. If the flag is False, then the killing action can be ignored.