There's been plenty said and written on the whole issue surrounding the likelihood of Knox and/or Sollecito being the "sort of people" who'd commit such a murder. FWIW, my views on the subject are as follows:
1) It's absolutely possible (although very rare in the whole universe of murders) for individuals with the same age profile, status, background and ostensible character traits as Knox and Sollecito to participate in brutal murders. It's therefore incorrect to assert that Knox or Sollecito simply couldn't have been involved owing to these factors alone.
2) However, I believe that it's unprecedented in recorded crime for two people who have been in a relationship for less than a week to engage in precipitously nefarious and dangerous behaviour that ends up in sexual assault and murder. For two people to engage in such behaviour necessitates either a very high level of mutual trust or a very high level of psychological control by one of the individuals over the other. It's all very well for ignorant pro-guilt commentators to cite Fred/Rose West, Karla Homolka/Paul Bernardo, Hindley/Brady etc, but there's an absolutely massive difference between these cases and Knox/Sollecito. All of those other couples had been in intense relationships for at least two years before they started offending together. And, incidentally, in all of those cases the male partner had prior history of engaging in extremely deviant solo behaviour prior to (and/or in the early stages of) the relationship with the partner. And by deviant I mean multiple theft, Peeping Tom activities, rape or murder.
3) So it's therefore appropriate to suggest that in the specific circumstances of the Kercher murder and the nascent level of the relationship between Knox and Sollecito (not to mention the Guede factor) it's extraordinarily unlikely that Knox and Sollecito would have mutually supported each other in the orgy of violence and sexual deviance that took place in the Perugia cottage that night. In fact, it's overwhelmingly more likely that the murder and sexual assault was the work of a sole deviant individual working alone and indulging his dark fantasies. That individual, of course, was Rudy Guede.
4) However, I would argue that it's still inappropriate to completely rule out the participation of Knox and Sollecito purely on the above grounds. No matter how vanishingly unlikely it is that they grouped up to murder Meredith, it's important to understand that this leaves a real (although tiny) chance that they were in fact involved. And that's where it's necessary to examine the evidence. In this case, there's zero evidence pointing towards the participation of Knox and/or Sollecito in Meredith's murder, and in fact - given that the ToD was probably between 9om and 9.30pm, and certainly before 10pm - there's every reason to believe that Knox and Sollecito were in Sollecito's apartment at the time of the murder.
5) Therefore, a combination of sociological analysis and an investigation of the evidence leads to two inescapable conclusions: a) Knox and Sollecito are absolutely definitely not guilty in law of the murder of Meredith Kercher; and b) the very strong likelihood is that neither Knox nor Sollecito had anything whatsoever to do with the murder.
