Mark Waterbury is an engineer and businessman from King County, just outside Seattle. He’s a key member of Friends of Amanda Knox, and has self-published a book on the Meredith Kercher case entitled The Monster of Perugia: The Framing of Amanda Knox.
Like Steve Moore, he begins his presentation at the Case for Innocence event with a somewhat unsatisfactory allegory involving animals. Amanda Knox and Raffaele Sollecito are two canaries choking in a mineshaft of DNA evidence. This image seems to turn logic on its head. Instead of using the evidence to determine guilt or innocence, the proposition seems to be that, if the evidence seems to incriminate the canaries, this should only serve to alert us that there is a problem with evidence. Knox and Sollecito stand at the “cutting edge”, Waterbury says, in exposing the failure of modern forensics.
Waterbury thinks that DNA evidence is all well and good, but that it is open to abuse. The reasons for distrusting what has been presented in the Kercher case are, for him, common sense. A detailed understanding of the science is not needed. For me, that was disappointing to hear, because I think that, if there are any problems with the DNA evidence in the case, then the technical detail is where we need to look, whether it is easy to understand or not.
Waterbury looks in particular at evidence regarding the knife alleged by prosecutors to have been used by Knox to stab Kercher. Knox’s DNA was found on the handle and a tiny amount of Kercher’s was found in a notch on the blade. Knox’s DNA, he suggests, can be explained because it was her boyfriend’s and she had used it for cooking. Maybe that’s possible.
Regarding the victim’s DNA, he points out that the knife underwent a presumptive test for blood, using the chemical TMB, which was negative. For Waterbury, this makes nonsense of the DNA finding. But, even assuming the negative test definitively means that the material was not blood (given the tiny size of the sample, I am not sure whether or not this is correct), I can’t see why it doesn’t still make perfect sense. The knife, it is said, was used to stab someone in the neck. The prosecution claim that it was thoroughly cleaned afterwards. It may well be that this removed all trace of blood. But a tiny piece of skin, muscle or arterial tissue, invisible to the naked eye and caught in a notch could surely have been left on the blade.
Next, Waterbury turns his attention to the fact that the the DNA results were amplified. He tells a story (which, to be honest, I found quite difficult to follow) about a device designed to detect “a very unusual material” which, on one occasion detected a toilet instead. But I’m not sure what the moral of the tale is. Somehow, it seems that he is linking this to the idea that contamination may have been an issue with the DNA testing.
The lab tested various samples which contained Kercher’s DNA. The crux of what Waterbury says is that, because the sample from the knife was so small that it required amplification, traces left by earlier tests could have been left on the equipment and revealed themselves during the amplification, effectively giving a false positive. But standard procedures should prevent this. According to Patrizia Stefanoni, who oversaw the testing, these were part of her procedure and the risk of such contamination was zero. So, Waterbury has identified a theoretical risk, but Stefanofi denies that it is a real risk. I would be very interested to see an expert assessment of Stefanofi’s work. Was there some as yet uncovered flaw in her procedure?
Waterbury says that the prosecution refuses to release the results of her “negative control tests” (i.e. tests between tests to check if any stray DNA is present). I don’t think he is correct on this point. During the original trial, Judge Massei compelled the prosecution to release all of Stefanofi’s notes and they did so, albeit reluctantly. In any event, what does Waterbury imagine that the notes show? Did she write: “I found the equipment to be contaminated with the victim’s DNA but I went ahead with the test anyway”? That seems unlikely.
Whilst it may be possible in principle, as Waterbury suggests, that Knox’s DNA got onto the handle of the knife prior to the murder (how likely that is is a question for the court), I don’t think he says anything that provides a real challenge to the finding that Kercher’s was on the blade. And, since the knife was found at Sollecito’s flat, it remains incriminating for our two canaries. I can’t see how this problem can be evaded.
I think Waterbury has chosen well in terms of what he is focussing on. If there is something wrong with Stafanoni’s negative control tests then that would significantly aid the defence. But I can’t see any good reason to suppose there was, unless you subscribe to Waterbury’s “mineshaft” thesis (i.e. you know from the outset that there must be an error somewhere, it’s just a question of identifying it).
The competence or otherwise of Stefanoni’s work is currently being assessed in Rome as part of the current appeal. If there are any legitimate grounds to doubt that she found Kercher’s DNA on the blade of the knife, those should soon be resolved one way or the other.