I don't think that law prescribes "1 in millions" certainty for evidence.
If you have a DNA evidence that restricts the possible perpetrators to one 100th of the population than it is still a good evidence.
Just think of a shoeprint. We know that tens of thousands of shoes of the same model and size are made and still shoeprints are used in trials as evidence. Rightly.
I understand Bolint, however I was just trying to relay what the issue is here. I think I understood why you appeared to be mocking the argument you were and just wanted to try to explain as it's
complicated. I also did a miserable job of it, the peril of attempting to post during football games.
The situation is basically this. The DNA experts found that the Y-haplotype "corresponded" to Raffaele's, thus that's an indication that whatever material that was on the bra-clasp
did actually come from Raffaele Sollecito regardless of how it got there. However with at least three male contributors to that y-haplotype, it becomes a bit easier to put together a specific y-haplotype profile, more or less for the same reasons that you have a better chance of winning the lottery if you can play three times as many numbers all at the same time.
Do you have those lotteries where you live where they have you pick five numbers out of 60 or so and then do the drawing? This is kinda like getting to pick fifteen numbers to play one of those, you obviously have a better chance of winning and it's not the same thing as having three separate tickets each of five numbers, your odds are much better with one ticket that allows you fifteen numbers. If you take a look at
this chart you might be able to see what I mean, they have one to three alleles at every loci on the y-haplotype. That means that there's at least three people contributing to it, and some of them might be partial contributors or that they share those alleles, kind of like them all sharing the same number, not uncommon in populations with a shared genetic heritage. There might even be more than three contributors who share all the numbers with the other three.
So even if one can put together 17 alleles that correspond exactly to Raffaele's y-haplotype, it is possible that it didn't actually come from Raffaele but is a complication of shared alleles, kinda like if they allowed you to buy three separate lottery tickets and use only the numbers from each that you needed. Now one can read
the electropherograms and see that one set seems to be dominant over the other two, and those generally correspond to the ones for Raffaele's haplotype,
suggesting that they all came from the same person and that would be one with Raffaele's haplotype. However that's
not an absolute, only one number needs to be off, and with this level DNA sometimes it can be highly variable, thus at one or more loci perhaps the one contributor who's alleles seem to be dominant showed up smaller and another of the ones that is generally smaller was higher for that loci.
So even though the y-haplotype 'corresponds' to Raffaele's it might not
actually have come from someone with Raffaele's y-haplotype! Perhaps C&V went through and determined this, I just don't remember reading this section, perhaps because I missed it due to the fact I read it as it was still incomplete and being translated. As far as I know they just said 'correspond' and I'm uncertain what exactly they meant by that. I would have expected a detailed analysis if they read the y-haplotype electropherogram for this purpose and I don't recall reading it and was kinda disappointed as that's the facet I was actually interested in the most regarding the bra-clasp.
However let's forget that and say that is Raffaele's y-haplotype, I can't help but wonder due to the refusal of Stefanoni to cough up the necessary data if they didn't do the same because they finally got pissed off at the reticence and knew they could flay her alive on everything else. Just to give you an idea of the scope of Stefanoni's malefeasance, she pretended there was only one male contributor to the clasp and the rest was 'stutter' basically, which is demonstrating an incompetence that defies belief, as any clown on the internet like myself can easily find out that's not true. Anyway, even if it is Raffaele's y-haplotype for
certain then we're left with what the judge was getting at which is what
real scientists say:
Massei 293 PMF said:
Speaking of the Y haplotype, which was also found in specimen 165B, Professor Tagliabracci made no criticism of the reading/interpretation, but emphasised that such analysis could exclude, but not establish, the presence of a given male subject.
The problem is, as Judge Hellmann said, there's no way of knowing with enough confidence just how rare that y-haplotype is at this juncture. Unlike normal DNA profiles where they can use math to determine just how likely it is that someone shares that same profile and they construct them (by 'looking' at parts of the 'string' more likely to be diverse) to be as unique as possible, these y-haplotypes by their very nature cannot be unique like one human's DNA is from another, with the exception of monozygotic (identical) twins.
It's a totally different way of calculating things, do you understand what I'm getting at, and what Professor Tagliabracci meant? It's more like blood type, yet at this juncture there's no way of knowing with confidence what percentage are 'O+' or 'AB-' to make that determination, which is why I posted that database. Due to the very nature of genetics, localized populations tend to share the factors that would go into determining it as well. Also keep in mind that with three male contributors any odds you do come up with are going to be significantly reduced for the same reason in a class of thirty odds are closer to 1:1 that someone shares your birthday rather than ~10:1 as most might naturally figure.
So to use your analogy, at this juncture we don't even know the rarity of each type of shoeprint, there's actually three different shoeprints to try to match increasing the odds, and it may very well be that one of the shoeprints looks like it matches but actually doesn't. It's
complicated, and even if it does match, everything else says it's probable that shoeprint doesn't have anything to do with the murder.
So if you see people saying that despite the suspicious circumstances that it might not even be Raffaele's DNA, that's because there's significant reasons to doubt that it is, and I too am utterly mystified they could do such a thing and do it so badly that I have to say that!
