Thanks for the link and the update.Hmm I know it's a theory but in my humble opinion it's not a very valid one because if you read the quote below from the Times a lot of backtracking seems to be happening over the forensic evidence supposedly found in the car.
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Yes, I see your point but since the theory has come up and at least seems plausible I think the possibility needs to be looked at carefully just to be sure. Being sure can't hurt the parents if they are innocent and if they are guilty it might result in recovery of body.
However, I am interested to hear of the evidence seeming to be melting away, especially that about the labs complaining that their results are being misused.