I think it is a Theor which has been suggested by people (maybe not on here)
Lenin - I think the prosecutions case was that Guede, Sollecito and Knox planned the whole thing. There was certainly emphasis put on their (knox and Sollecito) phones being turned off at a certain point and Knox and Guede knowing eachother.
Guede's story is that after the consentual sexual contact with meredith he was in the toilet when Meredith was atttacked - at first by someone he didn't know and then after several changes to his story by AK and RS who he says he could clearly identify.
The prosecution didn't present Guede's version of events as what happened. they believe that all three were involved.
There is no evidence to suggest that AK and RS were all over the crime scene, though there is plenty to show that Guede was.
I am pretty sure none of them were high on drugs or claimed to be.
The reality is their stories only changed under loong questioning at the police station when they were being interviewed before they were arrested. They both very soon, as far as I am aware, went back to their original statements that they were together.
part of the prosecutions case lies in the different timings of phone calls, arrival at the house etc which don't tally with timings given by the police who arrived to investigate the discovery of Meredith's mobile phones in a nearby garden.