I've always thought this. I remember not long after she went missing they found traces of her blood in the parents car and their response was that she had a lot of nose bleeds.
That is a VERY big accusation to throw at them, and i do hope these aren't a concoction of lies.
Then again, if this is false, the McCann's would sue them vigorously. God, this is all so f**ked up. I couldn't deal if the parents were playing the public for all these years.