Now, another further problem in your reasonin, to me, it is the apparent totally adversarial setting. You see two sides: one must be "the good guys", and the other is bad or wrong.
This is fundamentally false from my point of view.
The suspects are guilty not because the police are good or bad - they are neither good nor bad to me, I see them as rather neutral. They are guilty because the police nore anyone else could fabricate that set of evidence, nor it is reasonable to assume that anyone fabricated any part of it.
I don't think most PIP think this way.
I, for one, think that the police and prosecution were, for a while at least, acting in good faith. I think that they genuinely believed that Amanda and Raff were guilty. I think there might have been some occasions where they broke a couple of rules (or guidelines as to best practice) because they believed that it was for the greater good (convicting the guilty for a heinous crime). I think that they were all ill-prepared for investigating a crime like this - and I think that most police forces are, as these kinds of crimes are relatively rare outside of big, violent metropolitan areas. I think that they acted on ignorance- how were they to know about false confessions and the science behind them?
There's plenty of shades of grey here, and in fact the kinds of narratives that would describe the ILE as heroes are all around us in the movies / books / tv shows. I mean, how familiar is this: renegade cop / prosecutor breaks the rules and generally does whatever it takes to solve a crime and catch a bad guy. I think it's an extremely damaging narrative (often, in TV shows, we the audience usually actually get to see the murder, so we have knowledge over and above that which the renegade cop has, which allows us to know he definitely has the right suspect. People then 'forget' that they do not have such knowledge in real life). But people are predisposed to have sympathy with it.
I think that at some point they stopped acting in good faith, and went into damage limitation / cover up mode. However, the existence of PGP such as you, Mach, who still genuinely believe in their guilt, based on this evidence, causes me to doubt this. It shows at least that it's possible to genuinely believe it.
6 years on, with all that time to look at the psychological phenomenon of false confessions, familiarise oneself with the guidelines relating to LCN DNA and forensic handling and collection, familiarise oneself with the shortcomings of witness evidence and behavioural evidence, by this point we have to conclude that what we're looking for might not be purposeful framing, but is at least WILLFUL ignorance.
I was in Perugia over the summer, and spoke in depth with someone who's followed the case closely, and written articles for the local media about the case. Although this man has a scientific background, when I asked him if he had read Saul Kassin's work on false confessions, he indicated that he had not. He therefore remained convinced that Amanda is a liar. When you are aware that there are scientific facts that have a bearing on your beliefs, and you choose to ignore it completely, you are not acting rationally. This is clearly a state of willful ignorance. When PGPs read the psychological evidence but dismiss it for no good reason, or argue that it is not descriptive of Amanda's interrogation for no good reason, this is also not good enough either. It amounts to a refusal to engage with the reasoning process.
Whether one precludes the reasoning process altogether by purposefully remaining ignorant of the facts, or refuses to follow evidence through to it's natural conclusions, this is enough for bad faith, and shows a failing which is at once intellectual and moral.