BobTheDonkey,
I think that one ought to do control experiments of the kind described below.
http://www.sciencespheres.com/2009/10/methods-of-polizia-pseudoscientificaa.html
Control experiments to check for this would have been simple. The clasp was retrieved from a pile of debris left by the fastidious investigators in Meredith's room, shown in the picture at the right. Testing a few other items from that pile to see if they, too, had picked up DNA dust from the floor would tell us whether there was anything special about the clasp. Of course, that wasn't done.
So we have “Raffaele's DNA was found on Meredith's bra clasp,” rather than, “Raffaele's DNA, along with DNA from lots of other people, was found at various random locations throughout Amanda's apartment, which he visited several times before the murder.” The first phrase sounds incriminating. The second, accurate phrase, shows how meaningless this test result is without a control experiment.
[end quote]
In response to a question from Fiona, We know from the appropriate video that there was also dust on the glove of the person who collected the clasp, which seems to run counter to the spirit of the DNA guidelines to which I have linked previously.
Without knowing the identities of the three others whose DNA is on the clasp, I would ask how they could be excluded as possible suspects.
Chris
Ahh, but if his DNA was so freely floating around as you've claimed, why was it not on anything else that was tested? There were 400+ swabs tested, that's 400+ swabs that work as controls.
Let's see, 400+ swabs didn't show any signs of his DNA, 1 that did. I'd say that 1 that did is pretty conclusive.
Again, how could only the bra clasp be cross-contaminated? Are you saying the door wasn't the source of the DNA? Or are you claiming that of all the places the DNA on the door could have contaminated, it managed to contaminate solely the clasp
and none of the other 400+ tested places including the hallway!