One of the reasons I suggested the hand towels as a possible source of contamination is that of all the places on which someone might leave their DNA, a bathroom hand towel would have to be a pretty strong candidate. Stefanoni actually argued - wrongly, according to the defence - that a 'rubbing' action is necessary to deposit DNA. Well with that theory, the action of someone drying their hands on the towel would be very likely to leave DNA.
Sollecito would almost certainly have used Amanda and Meredith's bathroom at some point during his visits, most likely on the day of 1 November when he'd cooked dinner at the cottage. The towels, of course, were taken from the small bathroom and were found next to and underneath the body, while the bra clasp was found in the same area (underneath the pillow to be sure, but there's no particular reason to think that was the case throughout the attack and its aftermath). DNA transfer from the bath towels would also explain the possible traces of DNA from other people on the clasp, especially given that those other people would most likely be Laura and Filomena; Sollecito could be identified through the Y chromosome test, while if the other contributors were all female, they would be much more difficult to identify.
I think your path of reasoning in assessing the probability of transfer from the towels is a little flawed (that the towel depositing DNA on just that spot is unlikely). Exactly the same argument can be made for the extreme unlikelihood of Sollecito depositing his DNA on just that point, even if he took part in the attack. What are the chances of Sollecito happening to not only touch the tiny metal hook of the bra, but also happening to leave his DNA on it - and not doing so on anything else in the room? Think of how many tests the scientific police did, how many traces of blood they tested - and Sollecito's DNA was only found on that one tiny spot! The odds are astronomical. Yet if we believe the scientific police, his DNA is there.
The point is that both arguments as to how the DNA got there are extremely unlikely, and there's no reason to think transfer from the towel is less probable than direct contact during the attack (note: you can't say 'it was more likely through direct contact because he cut the bra clasp', because the only evidence we have that he cut the bra clasp is the DNA itself - the reasoning would be circular). And in fact, given that his DNA was found nowhere else, it could be argued that transfer from the towels or elsewhere is more likely than direct contact, which surely would have left some other trace. However, I'm happy to say that both theories are equally likely (or unlikely).
I agree that this theory would rule out forensic contamination, but I'm not sure that makes it any less probable. In terms of testing the towels, I don't think any of them could be accurately tested; one of them had mildewed, and the other two were too saturated with blood to properly test (this is one reason given by the judge in Guede's appeal for refusing further testing on the towels).
If the objection consists in making an analogy between Sollecito leaving DNA in a single spot - the bra clasp - and the theory of transfert via towel, I disagree, and I found the two cases very different.
1. First of all, the number of DNA findings in Meredith's room is not an issue, and was not an issue in my argument. Rudy Guede left only three DNA traces on items, which is more than one, but not a number of a different magnitude. This is the size of numbers if we are speaking about items traces that where sampled. Maybe there were 30 DNA traces of Rudy in the room and only 10% were sampled, maybe there where 10 traces of Sollecito in the rom, and you would have a finding with the same ratio.
2. The transfer from Raffaele touching the bra clasp would be a direct transfer (like all others were deemed to be direct transfers). While the transfer from a towel would be secondary, and the likeliness of leave a secondary transfer is something entirely different. It is about very different odds from touching an object. A towel would contain only microscopic tiny amounts of DNA, a minuscle amount, not quite like a human finger, and also it would be extremely unlikely to transfer this amount on a precise spot.
3. There is no evidence of towels with Sollecito's DNA. One or two the towels were analysed and DNA samples from Sollecito were not found. Moreover, Sollecito's defence did not ask for furthr tests, and did not put forward this theory, and what the defence does and says on the matter is important in the case as you know: the defence in fact proposes a different theory based on forensic error. The whole thing has, as an effect, the fact that there is no evidence of presence of Sollecito's DNA on a towel, so this towel with DNA needed to build the theory is missing.
4. The relation between the towel and the bra hook is very weak. I mean it is about the less likely object to have contact with the towel, and expecially unlikely to have a strong contact with the towel. This tiny clasp would have fallen on the ground during the attack and was under the pillow when the victim was placed in her last position. The towels enter into play after the stabbing. You could imagine that towels could have been used extensively on the floor to clean blood, wiping and brushing and maybe over the piece pf bra clasp. But this kind of activity would be a clean up, and a clean up incriminates Amanda Knox. The bra clasp is an object of no weight and we may think the only way it could have a contact with the towel is getting catchd and wrapped into a towel inadvertently, and then dropped exactly where it was found underneath the body. This complication is needed to build a dynamic. But the bra clasp nevertheless is not stained with blood and the towels are soaked with blood. To conclude, there is no
reason to think the towels should leave their secondary transfer
on that piece of item.
5. Apparently - although I am not sure about the whole set of loci - the fragments of DNA don't need Laura and Filomena to be explained. Moreover, the towels were from the small bathroom, not used by Laura and Filomena. If you start thinking about a towel from the other bathroom, things get complicate because Rudy Guede - dirty with blood on his hands and clothes, cuts on his hands, bloody shoes or allegedly bloody feet, allegedly tiny glass fragments - didn't leave any trace of himself nor of Meredith in the big bathroom, while traces of Meredith's blood are abundant in the other bathroom. So I would not easilly believe
Rudy as lone perpetrator walked in the other bathroom to get a towel.
