Meredith Kercher's parents have a personal interest in Knox/Sollecito being found guilty.

[pnwmom]

I kept wondering why Kercher's parents seem to have so much invested in the guilt of Knox and Sollecito, even though there is a 3rd person -- a known burglar -- who's indisputably linked to the crime by way of DNA, handprints, fingerprints, shoe prints, etc. and who is known to carry a knife.

And then it dawned on me. If Guede is the only killer, that will mean the end of the parents' civil suit. There will be no place else for their anger and grief to go. (Suing Guede alone would be a monumental waste of time and money, since he has none. No lawyer would want that case.)

But if they believe Knox and Sollecito to be the killers, then they can throw all that anguish into their civil lawsuit -- and perhaps win some blood money.

I don't think this is their CONSCIOUS reason for believing in the guilt of Knox and Sollecito, despite the abysmal lack of solid evidence. But it could be, unconsciously, part of why they're clinging to their belief in this unethical prosecutor and his pathetic case. They're clinging to their fury and their grief, because it's all they have left. Nothing will bring back their beloved daughter.