If I remember SH's theory correctly, it is totally immaterial (to his/her theory) where either of them were both between 9 and 10 pm, as well as at T.O.D. (regardless as to whether or not that time period or the T.O.D. coincided.)
SH's theory (and he can correct me if I am wrong) is something akin to Knox feeling guilty that she felt she had some indirect association with the murder, and then after that had happened returned to the cottage to effect a clean-up to mask who had done it.
Strangley this theory has legs among at least two journalists lately. One if Barbie Nadeau, whose favourite phrase is, "Knox knows more that she's telling us." Apparently CNN's Cuomo used that phrase recently too.
I saved a note from when Sherlock was kind enough to actually provide his theory
Author : Sherlock Holmes
Date : 26th April 2013 09:31 AM
Well, here are some things I believe are possible, but not written in stone
1) I don't believe Amanda or Ralf had anything to do with the murder
2) Amanda and Ralf did not stay at Raf's house that evening
3) The broken window may or may not have been staged, it really does not matter, if staged, Amanda and Ralf did it, but it does not matter, I'm leaning towards Rudi broke in before Meredith came home, the reason it does not matter is because of #4
4) Amanda or Raf, definitely locked Meredith's door, I can see no other alternative to this
5) The mistake Amanda and Ralf made, was not calling the police the night it happened. I believe there was a reason for this initially, but when it became apparent there was a murder, it was too late, or so they thought.
There he is clearly leaving Amanda and Raffaele out of the cottage while the murder is committed by Rudy Guede alone. So, why is he now trying to put them out of Raffaele's flat between 21:00 and 22:00?
There are a few points he appears to get stuck on. One is believing the only way Raffaele's DNA profile could be found on that clasp is for Raffaele to have been there after the murder:
Because I find it most unlikely that Raff had these balls of DNA rolling around the apartment, I believe he was there only for a few hours on Nov 1st and about an hour on Nov 2nd, 3/4 hours at most, while people that lived there would be thousands of hours, why wasn't their DNA on the clasp. Now if you want to say it was deliberately put there that would be far more likely, though I don't know why this would happen either.
Apparently sherlock just missed my recent post about the possible ways for that profile to be found.
Another being the Luminol tracts which only show Rudy walking out of Meredith's room without locking the door at that time.
Author : Sherlock Holmes
Date : 3rd June 2013 12:10 PM
No one ever said Rudy walked straight out the front door, that's just some things some PIP's like to say to think they are somehow discrediting someone, the shoe print evidence clearly shows he walked around at the front door, maybe collecting his coat, maybe peeking out the front door waiting for the coast to be clear, who knows, however, it also shows that he did not return, even when tested with Lumina.
The Luminol evidence is not a complete survey of the hallway and does not include tracks smaller than a complete footprint so there is no way that it can be used to exclude a return trip to find the keys to unlock the front door.