Now, the probabilities.
No, it's not a matter of proving it. It's a matter of proving that it's probable.
What is the probability of tertiary transfer of skin cells through drying hands on a towel and then touching an item, and transfer the DNA there, and specifically there.
You know because, if we argue about what's in rerum natura, we should know it is possible to buy a lottery ticket and win. But it is not reasonable to expect this will happen. What's just possible is not exactly what you need to dismiss a piece of evidence. You need much more than that.
Based on the same logic - probable as winning a lottery ticket - a defence lawyer could argue that each finding of Rudy Guede's DNA in the murder room was due to innocent reasons, a tertiary transfer of the same kind or another innocent reason. And there are only four instances of Guede's DNA in the room, some of them even only yielding a compatible Y-chromosome and no X profile.
Based on a reasoning in rerum natura, a defence lawyer may also argue that bruises on the victim's vagina had innocent reasons not related to sexual violence.
Obviously, no judge would consider such arguments.
The arguments above mean just failure to understanding anything about how evidence works.
It doesn't matter at all what you think of Stefanoni. There is simply no evidence of the contamination claimed by the defence.
Not me, but the defence should tell her, and they should tell her during the incidente probatorio. Or they should explain the judge clearly what they need to do with the data, what their theory of contamination is. Something the defence did not do. We all know the defence did not submit such requests of seeing raw data of DNA tests, there is no trace of such instance in the preliminary hearing, in the defence appeals reasons nor in requests to the supreme court.
Mach, I think you (and the Italian courts on Chieffi's decision) are misunderstanding the nature of contamination in regards to DNA testing.
Contamination is always present, we don't live in a vacuum in space, but awash in an ocean of biological matter.
A purpose of any DNA finding is to show that contamination is not a factor in the result, or a low enough factor so as to demonstrate the reliable attribution of a sample.
IIUC, that's the purpose of the negative and positive controls, sample size, and replicable results to show its not a one off accident.
In this case, Stef was not using internationally recognized protocols, performed single tests for the two purportedly incriminating results against Amanda and Raf (knife and bra clasp), misrepresented the sample size in court, concealed her control samples and other data, and claimed she never had contamination in her lab.
One must also consider the context, in comparing this minute result from Raf on the bra clasp to all the samples found from Rudy.
It's not just the sample size that should disqualify the finding on the bra-clasp as regards to incriminating Raf, it the lack of any other evidence of any kind of his presence in the room, or at the cottage at the time Meredith was attacked.
Where as Rudy's footsteps are in Meredith's wet blood, his fingerprints in wet blood, his DNA in multiple locations, on and in her body, and on her purse, and he talks about how much money she had and where, with money missing. And Rudy admits he was there, in the room, stepping in her wet blood. He just tells a crazy story that tries to deny his own guilt, and quite different from the first story he is recorded having told to his friend on skype while on the run in germany, when he said Amanda had nothing to do with it and didn't know Raf at all.
The knife blade sample that supposedly shows Meredith's DNA was taken from a "scratch" on the blade no one else could see, finding a DNA sample of Meredith that no one else could be confident existed, and defies common sense.
The bra clasp sample was a mixed result in such small quantity, accompanied by multiple other contributors, and there no reason for this finding to be more incriminating against Raf than against any of the rest of them. The finding is in question because of the circumstances of collection and the documented problems, and lack of documentation at the lab. And it is unsupported by any other contextual evidence of Raf's presence. And Dr Peter Gill has said it is the type of profile result he would expect to see from a contamination event.
You're just blindly clinging to these false results, as you blindly cling to this wrongful conviction.
You don't get to make up scientific standards, nor does any judge any wherein the world. It's a clear miscarriage of justice. I hope Italy saves themselves further disgrace by annulling these false convictions of amanda and Raf in MArch, and exonerates them as early as possible.