But if the evidence is so obvious, as you and others claim, why are they sticking to their story? Are they just stupid? Is the conspiracy that strong? Or is the truth not quite as obvious as you portray on this thread?
It's never crossed your mind that people don't like being shown to be incompetent? This is true of someone packing paperclips - let alone someone charged with upholding law and order and solving serious crimes.
The fact is that the police/prosecutors were under huge pressure to solve this crime from the 2nd November onwards. This pressure was caused by a number of factors: the high-profile and grisly nature of the murder; the international dimensions to it (and the consequent presence of the international media, which in turn further piqued the interest of the Italian media); the apparent fact that students were deserting Perugia in large numbers in fear for their safety; and the fact that the Perugia police/prosecutors had demonstrably bungled their investigation into the murder of and Italian student almost exactly a year previously (and had been severely criticised as a result).
It's abundantly clear that the police and prosecutors thought they'd "solved the crime" by the evening of November 5th. The way in which they interrogated Knox and Sollecito in the following hours, coupled with the statements made by Perugia Police Chief de Felice the following day, are a clear indication of this. There was an almost audible exhalation of relief from police and prosecutors on the 6th November (coupled with unseemly levels of triumphalism), which reflected the following thinking on behalf of police/prosecutors:
"See! You (the public and the media) can have confidence in our investigative skills and competence! We solved the crime in less than four days, using all our skill, judgement and resources! People of Perugia can sleep well in their beds again, confident that the law enforcement community is easily up to the task of protecting them and identifying anyone committing serious criminal acts."
But the police/prosecutors soon discovered that they
hadn't solved the crime. It turned out that their belief in Lumumba's involvement (which they had formulated long before they convinced Knox to name Lumumba as the murderer) was incorrect, that there was essentially no evidence linking Knox or Sollecito to the murder, and that there was in fact solid evidence (a bloody hand print in Meredith's room, that was compared to police print databases) placing another person altogether - Rudy Guede - at the scene of the murder. Suddenly, the police and prosecutors were looking as if they had totally bungled the initial investigation, and that they had incorrectly rushed to an early judgement.
Faced with this situation, the police/prosecutors obviously decided that the best strategy to adopt (i.e. the one that made them look the least incompetent) was the following: 1) Simply substitute Guede for Lumumba in the original narrative, and claim that it was Knox who deviously led them in the wrong direction over the identity of the "third man"; 2) Claim that it was dogged police work that had exonerated Lumumba - even though it was no thanks to the police that a Swiss professor travelled to Perugia under his own initiative to provide Lumumba with a solid alibi; 3) tailor their interpretation of the scant evidence to support the Knox/Sollecito/Guede 3-way assault; and 4) Try a number of often-ludicrous motivation theories to try to explain why these three people - who barely knew each other - would have teamed up to brutally kill the housemate of one of the alleged perpetrators (ranging from satanic rituals, through to sex-games-gone-wrong, through to some sort extreme jealousy towards the victim).
And that's how it happened. No conspiracy. just a strong desire to be shown to be competent and efficient (and, more importantly,
not to be exposed as incompetent, inefficient and not fit-for-purpose). It can be explained simply though basic human nature - particularly when egotistical, arrogant, power-hungry individuals are involved.