I don't really think he's alive and well, but with the limited information we have I don't discount it being possible. I don't discount anything being possible at this point.
Whether foul play is involved, or David just wanted to make it *look* like foul play is involved, is there anything we know so far that gives any definitive answers? If there is I haven't seen it.
In some ways this seems SO out-of-character, and SO suspicious, that it almost seems like exactly the kind of thing a person might do if they didn't want family and friends to suspect it was their choice.