I'm reluctant to revive this thread, particularly as I didn't know Mike. (Looks like I really missed something).
But in case anyone wants to follow the NTSB investigation, here are two links to the preliminary accident report, FYI:
http://www.ntsb.gov/aviationquery/br...10X93918&key=1
http://dms.ntsb.gov/aviation/Acciden...2013120000.pdf
There's a little more data in the .pdf report if you know the NTSB format, but BLUF there's nothing really obvious. Could be pilot incapacitation or (most likely, in a helicopter) a mechanical failure. They should have had plenty of fuel (55 gals plus 10 in cans, minus one hour's flight 28 yields 27 if they didn't refuel for the second flight, 37 if they did, and the 206 burns about 28 gph), and the pilot should have been able to land safely if he ran out or had a simple engine failure.
It doesn't appear NTSB went to the scene, but someone from FAA did on their behalf. Between the lines, it seems clear that the accident was unsurvivable and the crew's death was instantaneous.
The NTSB will probably post a factual report before the end of the summer, unless there is something that's taking a long time to analyze.