Multi-Symbolism
Astraea has said it well --yet, there are some surprising indicators that can be found. Natal VENUS in a lunar return chart has shown up in many charts that I have done where a death is involved. Venus, of course, balances things and for many people it may be appropriate that they sort of clean up things before passing over.
As for other indicators, I have seen many after the fact but none seem to be "concrete" or even highly "possible" before the fact. I think we are all a little too complex in our make up and in the manner we choose to use these symbols to represent the actions and timing of life's milestones.
I've done "reverse Solar Return charts" from the time/date of death for several criminals that have been executed. These charts show how the potential of the birth chart was actualized, as well as showed the crime that led to their ordered demise. But, again, no definitive one planet or combination of factors that says "death." Dave.