Another person did and said no one else was there. The accused came up with an airtight alibi. A witness came forward that saw the crime and said the defendant wasn't there. Here, we a case go to trial after a year and two witnesses were brought forward that testified the defendant had not been the aggressor. He was found not guilty as that all we have, but the jury added on that he had been the victim of an assault and all his legal fees were paid.
In Italy it would have been a para 1.
I completely disagree with your assumptions and examples.
1. Another person did [confessed to the crime (?)] and said no one else was there.
The problem with this example: the other person's statement may be false - the confession may be false and/or the statement no one else was there may be false.
There are US cases where police have obtained a false confession from a suspect, X, for example, for rape and murder, and later DNA analysis clears (to a reasonable person) the person who confessed - because there was no DNA of that suspect detected on the victim or even in the crime scene. So if suspect X stated that another possible suspect, Y, was not a the crime scene, that would not finally be credible exculpatory evidence benefiting Y.
Or X may indeed have been there, but chooses to protect Y.
2. The air-tight alibi may be fraudulent.
3. A similar argument with the witness. Witness identifications are notoriously unreliable.
My argument is that for each of your examples, and any example that may be produced, the full relevant range of evidence should be examined and verified before final conclusions are drawn.
In the Knox - Sollecito case, in order for the prosecution case to hold, there would need to have been a selective DNA clean-up of the murder room. That is a physical impossibility (with current technology), and is one of the strongest possible indications that Knox and Sollecito are innocent. But verification of this exculpatory evidence requires gathering appropriate DNA samples based on accepted scientifically-based forensic practices and obtaining DNA reference samples from Knox and Sollecito. And, of course, not allowing contamination and not allowing fraudulent lab work or analysis.
However, this would still be a process of the evaluation of evidence - although it should have been done and resolved fully in the early days of the case and no arrests of Knox, Sollecito, or Lumumba made or trial held. But the prosecution case is still defeated by the
contradiction between the evidence - which is exculpatory - and the possibility of Knox and Sollecito committing the crime. Thus, the rationale for the acquittal is found under CPP Article 530.2.
For a judge to find that an accused has not committed a crime (barring an amnesty, self-defense, lack of mental responsibility, etc.) requires an examination of evidence. Otherwise, for the judge to decide that the accused has not committed the crime, the judge must somehow be a source of "Truth" or communing with some source of absolute knowledge. Perhaps this concept relates to the inquisitorial justice system's foundations in religious courts.
