If I understand correctly, it seems that all those that tested the DNA on the bra clasp have concluded that Sollecito's DNA is on the clasp. Sollecito's defense has been that the only reason it is there is due to contamination. This argument is based on the fact that the fabric with the clasp was collected six weeks after the murder. The fact that Meredith had recently parted with a boyfriend in England and found a new boyfriend in Italy, and that additional male DNA was on the clasp, does not change this fact.
I seem to recall that the cottage was a sealed crime scene throughout the six weeks. Someone did break into the cottage via the kitchen window at some point, although I don't remember if it was before or after the clasp was collected. If the DNA on the clasp is a result of contamination, then it had to come from a source other than Sollecito. That would mean that it was contaminated either at the crime scene or in the lab.
If it was contaminated at the crime scene, that would mean that Sollecito's DNA was in the cottage and someone inadvertently put it on the clasp. It would make far more sense if Filomina's DNA had been transferred to the clasp, as she had lived there the longest. Sollecito had only been in the cottage once or twice that I know of, one of those times being the last day that Meredith was alive. It seems very unlikely that his DNA was transferred at the crime scene given the absence of him at the cottage in general.
The alternative is that, if the DNA on the clasp is a result of contamination, it occurred in the lab. If one piece of evidence was contaminated at the lab, then it's logical to assume that other evidence was similarly contaminated. The problem with this is that none of Guede's DNA was contaminated at the lab. It seems rather unlikely that there would be only one instance of contamination and it just happened to implicate the prime suspect, and there were no other instances of contamination at the lab.
What am I missing? What is the theory regarding contamination of the bra clasp? Crime scene contamination? Lab contamination? Contamination is always a possibility and it doesn't matter how it happened?
He lies to explain Meredith's DNA on the knife and alleges contamination to explain his DNA on her clasp?
"Murder victim Meredith Kercher's DNA was found on a kitchen knife because suspect Raffaele Sollecito had once "pricked" her with it while cooking, he has claimed in his leaked prison diary.
Computer studies student Sollecito, 24, made the suggestion in a 40-page notebook given to his lawyers and entitled "Notes on a Prison Journey.
...
In one entry Sollecito referred to the eight-inch black handled knife, which was found in his apartment, with DNA from Meredith on the tip and Knox's near the handle.
He wrote: "
The fact there is Meredith's DNA on the kitchen knife is because once when we were all cooking together I accidentally pricked her hand. I apologised immediately and she said it was not a problem."
However police have spoken to several of Meredith's friends who have all told detectives that
Meredith, from Coulsdon, Surrey, had never been to Sollecito's house."
http://www.dailymail.co.uk/news/art...-DNA-knife-pricked-cooking.html#ixzz2hEQdhaKO