Nothing secret. He lived in Landrum South Caroline.
His wife is Lillian Maresch(Lilly). He spoke about here a few times. (however I don't believe they were married). They don't have children. They met each other when he was already over 50 (if I'm not wrong). Lily has a Ph.D. in Psychology. She did the gallbladder flush also. She flushed out a very big stone (he wrote about this in his book gallbladder flush).
She is a very nice person. I've read things from here on the net.
I couldn't find anything as well about his death, no obituary info, no newspaper info. I don't understand why the ener-chi family hides (till yet) the cause of his death. The only reason maybe can be to keep on selling his books. I don't know if this will work because most people will suspect the teachings about health when the teacher passed away at very young age and we don't know why. However I hope I'm wrong and I hope we will hear the (real) truth soon. Andreas was a very nice man with great insights and a lot of compassion for other people.