This is the deal about Nencini's treatment of the bra-clasp.
Nencini needs to defeat the notion that there is contamination on that clasp. Why? Well, because there are five somewhat partial profiles of DNA (one female and four male), and to convict Nencini needs to show that Raffaele's profile is:
1) on the clasp
2) there for a non-innocent reason.
.... and that the rest are there for innocent reason.
The first sample is Meredith's, obvious there for an innocent and explainable reason.
The second sample is a Y-Haplotype. Because of its make-up, Rudy Guede can be ruled out. However, Raffaele belongs to a group of men which does fit that profile. So it cannot be said to positively I.D. him, but it cannot be ruled out.
So far, Nencini is echoing the Massei report published in 2010. Yet Nencini does something one would think he shouldn't do, not with Cassazione in Mar 2103 overturning the acquittals. Part of the reason why Cassazione did that was because they found fault with Hellmann relying upon Conti-Vecchiotti's DNA analysis which trashed Police lab's Stefanoni's report - a report which was accepted in total, completely uncritically by Massei in 2010.
Nencini, though, does something strange - he accepts the findings of Conti-Vecchiotti in relation to the clasp!!!! Nencini concedes that there are four identifiable extra male-samples: three plus a group of men where Raffaelecannot be ruled out. Nencini implicitly brings Conti-Vecchiotti back from the dead!
So - the third sample is also Y-genetic material. No one knows who it belongs to - no control/comparative-samples were taken at the scene. But remember, Nencini is trying to argue that all the rest of these clasp samples were there by innocent means.
So without testing it, Nencini invents out of whole cloth, pulls out of thin air that this sample MUST be Meredith's boyfriend's. Why? Well, if it isn't then there's a third unknown male in the room at the time of the murder, or....
..... there's contamination. So Nencini just makes it up, invents it: that it is Meredith's boyfriend's/ And why not..... she was sexually active and being a responsible adult even borrow contraception from Knox, her flatmate.
But wait a minute. Nencini has implicitly brought C&V back from Cassazione-death. There are two more male DNA samples on that clasp. And Nencini has to find some sort of explanation for them being there which:
1) is innocent
2) which does not suggest contamination
So what does Nencini do with samples #4 and #5? He assigns them to "amica", two unknown of Meredith's women friends who could have come into contact with the bra for innocent reasons. Not one but TWO women with Y-genetic material.
Nencini has brilliantly proven that four of the five samples on the clasp are there for innocent reasons, not suggestive of contamination. And the fifth has to be Raffaele's, there for sinister reasons even though Raffaele only belongs to a large group of men owning that Y-Haplotype.
Why might this not be part of the defence's appeal? Because for the defence to suggest that any of the officers of any of the courts had either been incompetent or criminal.....
...... instead of the higher court investigating that claim.....
...... the defence themselves get charged with defamation or calunnia.
That's how it works in Italy.