I don't think that two men committing the crime is outside the realm of possibility. I suspect Guede and Sollecito killed her, and Knox covered for Sollecito. Knox's defence might have successfully discredited elements of the prosecution's case, but there were elements that they never explained - like the way the police found footprints belonging to Knox and Sollectio when they swept the scene with luminol; or the way Sollecito and Knox claimed that they were together the morning Kercher was murdered and never got out of bed until ten in the morning, but his phone was active four hours beforehand; or the way they called the carabinieri to report the break-in and claimed nothing was stolen, but never acknowledged the presence of local police at the time, and the local police had not established that nothing was stolen. Even their behaviour in the immediate aftermath of the discovery was bizarre - completely disconnected and unconcerned. She wasn't a helpless and naïve foreigner who was completely defenceless in the face of an unfamiliar justice system until such time as she started getting some image management from her supporters.