It comes down to Stefanoni's "stutter" versus C&V's "other minor contributor/contributors".
It sounds to me a matter of academic opinion. The traces that matter are the ones that belong to Sollecito, identified by name and also called a major contributor.
This trial is an accruement of facts and evidence that form a narrative. It is a circumstantial case. Italian rules apply, not English or American rules.
I see it as one more arrow pointing to the defendant, not as THE arrow pointing to Sollecito.
It is just my layman's opinion. Will the judges fixate on "unreliable" or will they fixate on the 16 Sollecito peaks on the clasp is anyone's guess. I have no idea how the Perugia judges will rule on it.
If you think it through, it's not evidence of anything at all at this stage.
The guilter dogma (before C&V demolished it) was that there was "abundant" DNA from Raffaele on the clasp,
and that this proved he had handled it. Now if there really was proof that Raffaele had handled that bra clasp he would have some serious explaining to do. However we now know from the C&V report that there was a tiny amount of DNA-bearing material if there was any at all, that proper tests to confirm that skin cells were present as opposed to the DNA coming from lab contamination were inexplicably not conducted, the test was not replicated and incompetent evidence handling destroyed the bra clasp before it could be re-examined.
Cynics might think that this is consistent with Stefanoni deliberately spiking the test run with Raffaele's DNA by one means or another, and then destroying the evidence so nobody could establish that she had done so. However we'll probably never know.
So take-home message #1 is: We now have is evidence that Raffaele's DNA got on to the bra clasp somehow, but contamination at the scene or contamination at the lab are explanations that cover that fact.
Then, and this is the bit that the guilters don't seem to grasp very well, we have extremely strong evidence that contamination occurred somewhere along the line. The existence of multiple DNA profiles on the clasp means either that lots of murderers handled the clasp (good luck with that theory) or that the DNA of non-murderers got on to that clasp somehow.
So do the math:
1. Raffaele's DNA got there either because he was a murderer,
or because the sample was contaminated.
2. We know the bra clasp was contaminated.
Once you have those two facts in hand you no longer need to invoke the zebra hypothesis of a totally unprecedented three-way murder and sexual assault involving people who barely knew each other or did not know each other at all, with no motive and a serious language barrier to overcome to boot. You've got a much more ordinary hypothesis to go to - the bra clasp got contaminated either in a house Raffaele had visited or in a lab storing "abundant" amounts of his DNA from other samples.
I suspect some guilters, the ones not very good at joined-up thinking, might respond by saying something like "Um, er, but there was
more of Raffaele's alleles than there were of the other peoples', more! More means something, right? It can't be contamination if it's more. It must mean he handled the bra clasp! I don't understand science but my uninformed guesswork is good enough for me". However absolutely nothing about the laws of the universe says that contaminating material must be a homogenous mix of DNA from every contributing source, and if you think about it that very idea is a bit weird.
With the evidence now in hand concluding that Raffele's DNA was on the bra clasp therefore he handled it at the time of the murder is pretty much like thinking that because your car won't start that the spark plugs have been stolen by midgets. You're ignoring multiple much more likely hypotheses that explain the available facts.
