Since reading Gaeton Fonzi's book, The Last Investigation, I have always believed that George D did indeed commit suicide. Afterall, it was recorded on a tape recording, with little evidence of foul play. I always remember George's quote to Mr. Fonzi:
"If there's one thing you remember from what I tell you........ Lee Oswald was smart as hell, no matter what anyone tells you."
George D, whom LHO called one of his "good friends", even though George later destroyed LHO in front of the Warren Commission, is one of the great mysteries of this investigation.