Let’s just address the knife since re-examining the entire case is beyond reasonable scope, to serve as a basis for whether I am just repeating “myths.” Here is an actual, incontrovertible fact about the knife:
In the final Italian Court of Cassation ruling on the matter, which is summarized by the New York Times ( Italy’s Highest Court Explains Decision to Clear Amanda Knox - The New York Times (nytimes.com) the court actually says that there was never proven blood on the knife. Why would the court say something like that if, as you suggest, it is so obvious that Kercher’s DNA was on the knife?
The reality is the DNA evidence purporting to link the knife to Kercher was heavily disputed for many years. It would be possible to post about this for hours, but I go back to–I give a lot of deference on such matters to Italy’s Court of Cassation. They are the experts in the Italian legal process, they also are working from the best source of information possible on the investigation–they had all of the original investigative work available to them and they also had of course all the work that was done in the years after the initial conviction. They also, unlike the True Crime community, are working from documents in their native tongue. A major issue with a lot of the True Crime community in this case, both the pro and anti Amanda side, is that the more detailed documents available are often only available in Italian, with only selected translations available. This means people who do not read Italian are left running translations through translation engines, which is fine for many uses but not great for analyzing complicated legal and technical literature.
There are a lot of twists and turns that occurred with the knife. For example Sollecito offered a weak explanation as to why it might have had Kercher’s DNA on it, most likely this was a lie, but it has never been denied that Sollecito and Knox have told numerous lies during the course of the investigations and trials. That’s unfortunate, but isn’t in and of itself enough to overcome problems with physical evidence.
The prosecution has always vigorously maintained the integrity of the knife’s DNA evidence, primarily because without it they have virtually no case at all in terms of physical evidence. But it is not accurate really to say the knife evidence was ever unambiguous. During the original trial for example the prosecution refused to disclose portions of the DNA testing, including the negative controls used. The DNA identification technique they used to detect Kercher’s DNA is not the most reliable, and is particularly prone to detect contaminations. Like I said, the arguments over the DNA evidence on the knife is complicated and could be argued about for days–but it should be made very clear, this wasn’t a bloody knife that had a smorgasbord of Kercher’s DNA on it. If it was the murder weapon, it was heavily cleaned. Even given that, the amount of DNA supposedly found on it was so small that it is actually possible it was the result of contamination–this is a point that has been argued vigorously by both sides, but again, I go back to the Italian Court of Cassation’s comments on it.
The knife simply was not stored or handled professionally, which if the knife was soaked in Kercher’s blood it would be one thing, but improperly handled evidence in which we don’t know if technicians had been freely handling other evidence and then possibly contaminating the knife is worrisome when the actual evidence is such a small amount of potential DNA. The Italian Court of Cassation obviously are not DNA experts, but they are experts in evidentiary law in Italy, and their ultimate opinion was that there was no clear evidence that Kercher’s blood was ever on the knife.
Is it possible the Court got it wrong? Of course, but as I said back in my original post on it–unlike the internet sleuths (and I don’t use that term in a derogatory fashion, I am no better informed), the Court of Cassation are experts in Italian law, Italian criminal investigations etc. It isn’t enough just to find disputed evidence arguing against their conclusion, for me to weigh more heavily than the ruling of this court would require significant and convincing evidence of error on their part, which I simply do not believe has ever been demonstrated by anyone.