Ultra-conspiracy theorising (double DNA knife)
This will be a long post setting out the reasons why I believe Patrizia Stefanoni's conduct should be investigated with a view to criminal proceedings for giving false evidence to the Perugia court. It concerns only the 'double DNA' knife.
Amanda Knox and Raffaele Sollecito did not murder Meredith Kercher. For one thing, they had no motive, for another they did not know Guede, it is very likely Meredith was attacked very soon after reaching home when computer records not destroyed by the cops show they were at Raffaele's place, Guede himself has been caught and his guilt completely accounts for everything at the crime scene. Finally, the crime scene contains no forensic evidence implicating the two.
So what? We all know this. Well, it means the knife taken from Raffaele's kitchen on 06 Nov 2007 (the day of the arrest) was never anywhere near the apartment or Meredith's body. Yet, the prosecution claimed to have discovered a trace of Meredith's blood ('presumed haematic substance') on the blade. There are only three possibilities which could account for this discovery, announced to the world on 14 Nov 2007:
1 inadvertent contamination of the blade in transit or of the sample taken from the blade or of the equipment used to generate the DNA profile;
2 misinterpretation of the result
3 fraud
We can discount 2, I think. Unlike the result for the bra clasp the egrams plainly show Meredith's unique DNA profile. *So, which of the other two is it?
Putting the science to one side, consider the circumstances first. The knife was the only one the cops tested. There were other knives at both apartments which were not tested. The knife is not compatible with the wounds or with the print in Meredith's blood which was found on the undersheet on her bed. At the hearing on 08 Nov 2007 before judge Matteini, when the prosecution was seeking authorisation for the continued detention of Amanda, Raffaele and Patrick, it was said that Raffaele's possession of a flick knife with an 8.5 centimetre blade which was 'compatible' with the wounds inflicted was among the inculpatory reasons. The kitchen knife had an 18 cm blade, twice as long. Used to its full length it would have created an exit wound. Added to all the other factors is the absurdity of the idea that either of them would have taken that knife out with them that evening or any other time.
It was said at the hearing before Matteini that Raffaele had more than one of these flick-knives and later on in the case, the suggestion was that he may have encouraged Amanda to carry a knife for her protection. Why wouldn't he have lent her his other flick knife in that case?
So the idea this knife was used to murder Meredith Kercher is already outlandish before any tests on it were carried out.
Now, let's look at the science. I am not a scientist myself but I think I have a handle on the major problems with the evidence. What I want anyone who has read this far to think about is what this knife tells us about the integrity of the prosecution. The dates I gave above are important. Remember the knife was seized on the day of the arrest and the results announced before Guede replaced Lumumba (i.e. before the case was solved).
The knife profile is 'low copy number'. The peaks on the graph (egram) are very small. Contamination is an acute issue in such cases and the battle between prosecution and defence largely revolved around this issue. It needs to be understood though that this was the battlefield only because of the nature of the proceedings. The defence teams had only to show a reasonable doubt to succeed. Contamination is far easier to argue than corruption and, fortunately, the gross inadequacies of Stefanoni's procedures afforded ample scope for such arguments. If Stefanoni instead had been on trial for perjury or perverting the course of justice the issues would have looked very different.
Let's work back from the egrams, of which there are two, showing the results of two runs. On the IIP public forum we recently had this from dna forensic consulting, responding to a question from geebee about the discrepancies between these two runs:
dna forensic consulting said:
Well, the discrepancies between the two run results are not consistent with the same amplified product being run twice even if on different instruments and on different days. The inversion in peak heights simply should not occur if the same thing is being run multiple times. The results actually look more like different amplification products. In my experience, contamination of DNA from previous runs has never been an issue with capillary electrophoresis. The design of the instruments provides excellent safeguards from this. Of course, anything can occur. The best environment for something like this to happen would be if prior to the knife blade sample being run, a sample with a very high level of Kercher’s DNA was run. It’s hard say what is going on here, but for many other reasons the data is essentially useless.
I have highlighted the words which suggest, to me, the means by which these runs might have been fraudulently produced. First run a sample with a very high level of Meredith's DNA, to contaminate the machine, and then run the supposed sample.
Bear in mind when thinking about this that the machine which performs the electrophoresis retains an integral digital record of the process. This is crucially important. It is this internal record which produces the egram. The record can be copied and passed around, like any other digital information. I believe it is absolutely standard in the US and the UK for the defence to have access to the so-called electronic data files (EDFs) the egrams themselves being merely a photoshopped product of the underlying data.
Three different negative controls are run at the same time as the sample being tested. IIUC the machine has four capillary tubes through which the sample and the three controls are run at the same time. The EDFs would contain information about the sample and the controls. It would show, for example, whether any controls were run and very much more besides, like the fried hard drives and missing recordings.
Stefanoni has never handed over the EDFs nor satisfactorily demonstrated that she performed the controls, although it would have been easy to have done so. Apart from suppressing information Stefanoni was also prepared to lie to the court. I will come back to that but mention one lie here. If DNA forensic consulting are right then she lied about these two runs, saying they came from the same sample. According to DNSFC, this is not so, Credit to geebee for raising it with them.
In a comparable case, which is in fact far less egregious, the FBI dismissed one of its own scientists for consistently neglecting one particular negative control over a two year period. It treated the entirety of her work as invalid and was forced to re-test all of it. Legal systems may differ from place to place but science is the same everywhere. The idea that some completely different standard can legitimately apply in Italy is absurd.
Still working backwards towards the sampling of the knife, Stefanoni did not know the quantity of DNA run through the electrophoresis machine, despite the fact this is an essential requirement in the interpretation of the result.
Further, she did not amplify the supposedly sampled DNA enough times. If you double the number 2 28 times you get a very large number. DNA extracted from blood or skin or whatever is amplified by doubling, normally over 28 cycles. Low copy number DNA should be subjected to 31 cycles to obtain a reliable result. Stefanoni used only 28, despite knowing the correct number. I have not worked out why she didn't simply lie about this. Maybe someone can help here.
Before amplification, the DNA must be quantified. Stefanoni told the court she used a procedure called quantitative PCR (qPCR) to do this, but this was not true. As she was discussing a key piece of evidence it seems reasonable to impute dishonesty rather than a poor memory, especially as this was coupled with another falsehood, that the quantity of DNA sampled amounted to several hundred picograms (a respectable amount). qPCR is extremely sensitive. It can measure DNA down to below 10 picograms. One human cell weighs 6 picograms. This machine also has internal electronic records which can be consulted to verify what she said. It is therefore significant that she did not, in fact, use qPCR. On the defensive, she claimed to have quantified the DNA with another machine, the Qubit Fluoremeter. This machine has two key differences from qPCR:
1 it retains no internal records. Like a pocket calculator it just gives a read out.
2 it cannot quantify very small quantities of DNA.
I am suggesting she did not use the Qubit Fluorometer either, as she had no extracted dna to quantify and knew she didn't. She said she used this device because of the unfalsifiability of the claim. Her story about what she did just doesn't add up. She said she sampled both sides of the blade, samples B and C. Both samples supposedly failed to register in the Qubit Fluorometer, each yielding a 'too low' result. The C sample was discarded, she said, but for no reason yet discerned, she claims she continued to test sample B with the results we have seen and to extract and amplify DNA from it.
Before supposedly quantifying sample B she supposedly tested it for blood, with negative result and also subjected it to a human species test, again with negative result. To the amazement of Conti and Vechiotti, she did not conduct any test to see what it was she sampled. I visualise this as putting the sample under a microscope and looking at it. It is possible I am wrong about this but pretend for a moment I am right (there will be an equivalent but perhaps less intelligible process of some kind). Imagine sampling something and not looking at it to see what it is. It's not pure DNA but some cellular material from which the DNA is extracted later. Stefanoni described at as 'presumed haematic substance'. Blood cells, perhaps, but not worth looking at? Why?
Stefanoni explained she sampled an area of the blade which had barely visible 'striations' (scratches). MWhen asked to locate these striations later she was unable to do so, nor could any of the defence experts do so.
That's about everything that is comprehensible to me. Attending the entire operation is a wholesale disregard for documentation and anti-contamination precautions (which I would rely on as showing a lack of professionalism rather than as suggesting contamination because I don't think inadvertent contamination is the explanation for all this).
Let's go back to 06 Nov 2007 and hypothesise that the prosecution just wanted a knife, any knife, with Meredith's DNA on the blade and Amanda's on the handle, so long as it was collected from Raffaele's apartment. That way it kills two birds with one stone. Let's further hypothesise a criminal conspiracy between the police and Stefanoni, formed on or around that date. A really simple one. Here Stef, 'find' DNA on that!
In this scenario, there is no sampling, no testing, no quantification and no amplification. There is a run through the electrophoresis device of a massive amount of Meredith's DNA, taken from somewhere else, followed by a run of an empty sample which shows up a low copy profile simply because of the previous run. No negative controls either. Why bother?
Now, what lies do you have to tell to support the big lie? I suggest they are the lies she actually told until further questions elicited new ones.
Q. How did you quantify the sample?
A. With qPCR
Q. And what was the quantity?
A. A few hundred picograms
Q. Let's have a look at your results
A. Sorry I used the Qubit, now I think about it, so there is nothing to look at
Q. Oh, what was the read out?
A. (thinks, can't say the Qubit's minimum threshold because then I would have to explain what became of the extract and I am not going to have anything left, so ... ) Too low
Q. What tests did you perform on the sample?
A. (thinks, I can't say 'nothing') er, blood and human species, both negative.
Q. Really? And what was it you sampled?
A. (thinks, i have nothing to show as there was never anything in the first place) I don't know, I didn't look to see.
Q. Oh. Why did you choose that part of the blade?
A. I saw a scratch.
Q. Can you point it out?
A (thinks - sh**!) strangely, no.
Q. You conducted negative controls of course.
A. Of course.
Q. Where are the results?
A. They are in the court file.
Q. No, they are not.
A. I assure you they are.
Q. We have not been able to find them unfortunately. May we see the EDFs?
A. No, the request is unprecedented and highly irregular
Q. You were dealing with low copy number DNA?
A. Yes
Q. What special precautions did you take *to prevent contamination?
A. None. But contamination cannot account for the result obtained.
Q. Agreed.
The whole thing being a set up from the beginning, there is no reason to suppose any of the steps Stefanoni says she took were actually taken, in the absence of objective evidence such as the EDFs would contain. An incompetent but essentially honest and diligent forensic scientist would have told a different story.
I am sure this can be improved in many ways but hope the broad outline is clear.