I agree that this appears to be an elevator failure. What pieces of the wreckage were retrieved? Was the horizontal stabilizer/elevator retrieved? Was the elevator bolt located (ripped out of the elevator, found in a side pocket, found in the trailer, etc). I have the ability to fly my Phoenix low level over the site on a suitable light east wind day and do a close search for the horizontal stab if it is missing. Finding the stab may be the key to solving this tragedy.