A very important day in the Amanda Knox appeal trial being held in Perugia, Italy.
Knox and her former boyfriend Raffaele Sollecito have been found guilty and sentenced to 26 and 25 years of prison respectively for the murder of British Erasmus student Meredith Kercher, at the cottage the two girls shared with two other roommates.
Amongst many troubling indices of guilt were a large kitchen knife found in the drawer of Raffaele's flat, a five-minute walk from the girls' cottage, and a small piece of Meredith's bra, the part of the clasp containing two hooks, which had been cut or torn off and separated from the rest of the bra during the attack on the unfortunate student.
The knife was tested for DNA, and while a sample of Amanda's was found on the handle, a tiny amount attributed to Meredith was found on the blade. As for the bra hooks, analysis in the forensic lab of the Scientific Police of Rome found a mixture of DNA coming from two people: a larger portion from Meredith and a small amount clearly identifiable as Raffaele's.
No other DNA of Raffaele was found in the room where Meredith was stabbed. Apart from the bra hooks, the clear evidence against him consists of a bloody footprint attributed to him found on the bathmat, and incontrovertible proof that he lied several times, in particular about his alibi.
Electropherograms (DNA graphs) of the sample found on the knife blade have been made public, and can be easily compared to available electropherograms of DNA known to be Meredith's. Although the peaks in the knife DNA are much lower, indicating a very tiny sample, the two graphs are obviously identical, with peak pairs located in precisely the same positions.
Amanda Knox's father, Curt Knox, and her mother, Edda Mellas, have commented in public at great length on the subject of the DNA found on the knife. Criticizing the work of the forensic biologist from Rome, Patrizia Stefanoni, the Knox/Mellas family has repeated in every media venue across the United States such messages as "the DNA on the knife has only a 1% chance of belonging to Meredith" or "the DNA on the knife could belong to half of Italy".
These statements are mathematical nonsense. It is quite undermining to their efforts at proving their daughter's innocence via a media blitz to make statements which are so mathematically wrong. The DNA on the knife corresponds at all thirteen genetic loci with that of Meredith Kercher. The chance that a different person produced that DNA sample is 1 in trillions or quadrillions - far more than the earth's population. If genetic analysis is used to identify human beings, it is because a complete sample (usually considered to be thirteen clear genetic loci, each one consisting of a pair of peaks) is considered just about 100% certain.
To say that the knife DNA has a "1% chance of belonging to Meredith" is simply a flagrant misuse of "numberspeak" in order to influence a public assumed to be either too ignorant to notice, or simply to have no access to the documents (electropherograms) that prove the opposite.
What the Knox/Mellas family should have said, and would have said loud and clear all along if they had been correctly advised from a mathematical point of view, is that the DNA from the knife blade clearly belongs to Meredith, but there is a clear possibility of that electropherogram being the result of contamination. This is, indeed, what Amanda Knox's lawyers held in court. The suggestion was dismissed, however, by the judge and jury in the court of first instance, because it was never explained how and where contamination might have occurred. The knife was collected by gloved investigators and packaged in a new unused envelope before being transmitted to the Rome laboratory for analysis, and Meredith had never set foot in Raffaele's house, so it seems extremely unlikely that any contamination occurred during the collection.
Raffaele further complicated his own situation by reacting with a completely unlikely story when he learned about Meredith's DNA on his knife. Instead of saying "That's impossible, she was never at my house" - or preserving a wise silence - he spun a tale about how it was normal that her DNA was on his knife because once he pricked her with it by accident while they were cooking together. Although he had once or twice cooked at the flat the girls' shared, he and Amanda both denied having ever taken the knife there, so his story sounded horribly like a lie.
Nevertheless, Raffaele and Amanda have had a break today. As a gesture of objectivity, the judge in their appeal trial handed the knife, the bra clasp, and all of the documents concerning them to a pair of objective, court-appointed experts from a university in Rome. Their report was handed in to the Court today, and leaked - already yesterday - to a number of sources.
The conclusions are that contamination may have occurred.
For the knife, it is pointed out in the report that given the tiny quantity of DNA on the blade, it should not have been analysed in the same laboratory where other samples of Meredith's DNA were already analysed, as the earlier samples can easily contaminate the later tinier ones. Proper protocol would have indicated taking the tiny knife sample to a different lab for analysis, but this was not done.
For the bra clasp, the report explains that there were any number of possibilities for contamination due to faulty collection procedures. It furthermore specifies that Dr. Stefanoni erred in attributing the DNA on the hooks to just two people, as there are clearly further contributors to the mix of DNA on the hooks, with more than one male. As no other male has been identified - neither the third accused perpetrator of the murder, Rudy Guede, nor Meredith's boyfriend, nor any other known person, this presence could be indicative of contamination.
There is a more evidence against Amanda Knox and Raffaele Sollecito: their own lies, mixed traces of Amanda's blood or DNA and Meredith's about the murder cottage, a painfully obvious effort at staging a faked burglary. Acquittal is far from certain. But the experts findings in the report turned in today will help, removing any proof of premeditation - such as bringing the knife from Raffaele's place to the cottage - and any actual guilty trace of Raffaele in the murder house, apart from a fuzzily outlined footprint.
The news reports that Amanda is singing and dancing today.
The experts' report will be presented in court on July 25.
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