I wish I knew too. It's sucks when a public figure dies and nobody outside of his family really knows. All that does is lead to speculation. At the end of the day it's their own business, I guess.
So, if they weren't murdered by somebody it really just comes down to:
1. Accidental death (car, heart attack, etc).
2. drugs
3. suicide
4. suicide by drugs
That really covers the whole spectrum once in gets down to it. Just a shame because if you can cover Di Giorgios bass parts then you are a mighty player. RIP.