One thing I wanted to mention from my own reflections, for whatever it is worth:
I am nearly fully convinced of Hendry's thesis of Guede as a lone-wolf burglar turned killer, and his belief that Mignini mistakenly focused on Knox and Sollecito. The ONLY problem I have , is with the duvet covering Meredith, and the locked bedroom door. Those 2 pieces of "evidence" are the sole ones which give me pause. Not that I think AK and RS were part of the crime, but as we spoke of at length in other threads, that they felt somehow culpable for Guede doing as he did. Just felt like airing this, as it is on my mind.
I see no reason why RG can't be the one who covered MK with the duvet. To my knowledge, NOBODY thinks RG is a serial killer who went to the cottage to kill somebody. So assuming he was surprised during a burglary, then he killed because he thought he had to, not because he wanted to. That's exactly a context that would produce the regret that might motivate a killer to cover his victim.
I don't believe we have ever determined whether MK's bedroom locked with a key or with a "trigger" when closed. Either way, RG had no way of knowing who else might arrive next or when they would appear. By locking MK's door, he made sure that another roommate arriving would (ETA
NOT) casually glance into MK's room and discover the body.
ON THE OTHER HAND, what would make AK and RS come upon MK's butchered body and feel so responsible they cover her and lock the door but don't call the police? And let's keep in mind, they BOTH have to agree on this course of action even they've only known each other for about a week.
Did they suggest the burglary to RG? How could they? They didn't know when MK would return home and they didn't know that one of the Italian flatmates (Laura?) would be gone for the night. They had no way of knowing when the cottage would be empty.
Did they suggest that RG make a sexual play for MK? This strikes me as incredibly unlikely. I'm sure it has happened, but it really seems to go against a woman's instinct toward a girlfriend. But assuming it happened, how does that make them guilty of conspiracy to rape and murder?
And why the extensive cover-up (which, let us remember, had to be devised and carried out without the two of them sharing fluency in any one language)? Surely it would be easier to turn around, agree to swear they knew nothing (if in fact they felt guilty), and call the police.
Occam's Razor = RG covered the body and locked the door on his way out.