Thursday, May 2, 2013

2. The Meredith Kercher Case - Back to the Drawing Board (Part Two)

Italy's Court of Cassation 


I started out this new series for the very simple reason that the Italian Court of Cassation recently quashed the Appeal Court's acquittal of both Amanda Knox and Raffaele Sollecito.

I then went on to point out a number of issues with regard to one of the most intriguing aspects of the case: the question of whether or not the break-in at the house at the Via della Pergola was, or was not, staged.

I will now turn to the most complex aspect of the trial: the DNA evidence. By this I mean both the DNA samples found on the so-called "double-DNA" knife and the sample found on Kercher's bra clasp.

In this second part,  I will be looking in greater detail at the Appeal Court's decision to appoint new experts, and will discuss that court's reasoning with regard to the DNA found on the knife. In Part Three, I will be focusing on the sample found on the bra clasp, and I'll make a few remarks about the idea of any of the samples being attributable to contamination in general. As always in this series, I will try to give some sort of indication of what the Court of Cassation  may have felt on the various issues raised.

A summary of the Courts' rulings

To put it very simply, the (original) Court of Assizes heard the arguments made by both the prosecution and the defence lawyers with regard to the DNA samples, the way those samples were tested and the reliability of the results procured; it then made its decision. Its decision was that the results obtained by the Scientific Police were reliable. That is: DNA found on a knife were attributable to both Knox and Kercher, whilst DNA found on a bra clasp discovered in Meredith's room was attributable to Sollecito. In other words, the knife must have been used to attack Meredith, whilst Sollecito must have been present when Meredith was attacked.

The Appeal Court, however, did not wish to make any similar assessment. Instead, it decided to appoint two new experts. It asked these experts a number of questions. Firstly, could the testing be done again? Secondly (if a new test was impossible), how reliable are the results from the original tests?

The experts answered as follows: no new testing can be done, whilst both the results with regard to the knife (in particular, the assertion that Kercher's DNA was present on the knife) and the bra clasp (that is, that Sollecito's DNA was present on the clasp) are to be considered unreliable.

In the case of the knife, the experts reached their conclusion because (a) it cannot be established that Kercher's DNA derived from blood; (b) the testing was done using a method known as Low Number Copying (LNC), whilst the internationally accepted precautions applicable to such a method of testing were not followed, and (c) it cannot be ruled out that the DNA found was the result of some form of contamination.

In the case of the bra clasp, the experts found that (a) it is not clear that the DNA found was attributable to any handling of the clasp by Sollecito, (b) it is not clear that it actually was Sollecito's DNA in the first place, and (c) this DNA, too, could be the result of contamination.

The Appeal court thereupon accepted the experts' conclusions and, in doing so, effectively disregarded the original court's findings.

Why appoint experts?

There are a number of things to be said with regard to the Appeal Court's approach to this matter.

The first of these is simply the question why the Appeal Court decided to pose these questions to new experts. After all, the experts for both the prosecution and the defence had argued their respective positions extensively before the original court. It is because of this that the original court decided to ignore a similar request made by the defence at that time. So why did the Appeal Court think otherwise?

To be frank, the Appeal Court's reasoning in this regard escapes me. In its ruling, that court attempts to set out that it's not just appointing new experts to answer questions already answered by the original experts (a situation which could obviously be repeated ad infinitum until the desired outcome, whatever that may be, would be achieved). It states that its decision is grounded in "legal reasoning" and that it's a question of "compensating for understandable gaps in knowledge in a particularly complex field".  

However, the questions the Appeal Court thereupon asks the experts are difficult to see in any other light than as a repetition of the work carried out by the experts before the Court of Assizes. Simply put, the Appeal Court requests the new experts to choose between the opposing views of the  prosecution and the defence. In doing so, it may well have gone further than is admissible under Italian law, and it may well have handed the decision with regard to the DNA evidence (a decision which the Appeal Court itself is required to make) into the hands of experts.

This, then, is the first issue with regard to the Appeal Court's ruling. As serious as it might seem in theory, though, it need not be all too important in practice. Firstly, the Court of Cassation could have felt that the decision to appoint new experts was ultimately justified, even if the way the Appeal Court went about it was not. And it might have thought that even if the appointment were not justified, the Appeal Court itself remedied the situation by sufficiently motivating why it found the findings of the experts correct.  

There is another aspect here, which is simply practical in nature. The fact of the matter is that, justified or not, new experts were appointed and they did answer the questions submitted to them. That's not something you can readily undo. It seems more or less impossible, for example, to take the experts' report totally out of the equation; any new appeal court, in handling the matter, will know of its existence.  

The Appeal Court's reasoning with regard to the knife

The second issue with regard to the Appeal Court's handling of this matter deals directly with the Appeal Court's (and the experts') views on the reliability of the DNA samples. Were the original results of the DNA testing accurate or weren't they?

Well, let's start with the samples found on the knife. No problem arises with regard to the Knox sample; all experts agree that the sample was accurate. Grave problems arise, however, with regard to the sample attributed to Kercher.

The main problem is that the sample was very, very small, and, as a result, LCN testing was done. Now, LCN testing is, or certainly was back in 2007 (when it was originally carried out in this case), somewhat controversial. It is only done is certain countries (Italy, obviously, but also countries like the UK). It is not entirely clear (that is, it is not generally accepted by the scientific community at large) what precautions should be taken - what protocols should be followed - in carrying out this type of testing.

In particular, the Appeal Court (and the experts) felt that reliable results from any LCN testing can only be obtained through multiple tests (or "runs"). The Scientific Police however, only conducted a single test. A single test that, according to the court and the experts, could not be repeated, since the DNA sample was used up in the testing.

As a result, court and experts felt that the results obtained from the test are unreliable.

There are, it seems to me, a few things to be said about this reasoning.

Firstly, I am not immediately convinced of the absolute necessity of conducting multiple tests. In general, I can well understand that, yes, multiple runs should be done, but I am not convinced the result from a single run should always be considered invalid. And I find the Appeal Court's reasoning on this matter - which effectively only points to views held by various experts in the field in general - rather lacklustre. The Appeal Court could, for example, have pointed out how high the chance is that the result from a single run could erroneously point to the wrong person in this particular case.

The Appeal Court, however, did not do so, leaving, to my mind, a serious gap in its reasoning (a gap which, it could be added, also appears in the experts' report). The problem here is simply that the Appeal Court seems to disregard the actual testing result itself; it does not ascertain to what extent that result (bearing in mind the way the testing was conductive) is indicative or perhaps even decisive. I find this rather surprising, given my understanding that the result was actually fairly clear cut: the Scientific Police's evaluation was simply that the DNA tested belonged to Kercher, and not, for example, that "it might belong" to Kercher, or some other equally vague attribution. (By itself this is not all that strange. If conducted incorrectly, or simply with too little material, LCN testing will, by and large, not lead to any significant result at all. You can test the DNA sample, but no match will be found. If, alternatively, a clear match is found, it would seem to me that the test was successful, and the attribution might well be correct. It would certainly be best to repeat the testing if possible, but such a repetition may not always be strictly necessary.)

As aside, I point out the Scientific Police, prior to conducting the test, invited the defence experts to be present. They did not, however, accept that invitation.

Secondly, the Appeal Court's (and the experts') assertion that the test cannot be replicated is almost certainly false. Technology progresses, and what it possible today is not what was possible back in 2007. Certainly the prosecution has alleged that a new test could be run, using today's methods. However, the Appeal Court has rejected the idea of this, and it is difficult to see this rejection in any other light than as a general suspicion of LCN testing as a whole. The Appeal Court clearly feels that any new test can only be conducted by a method still "in development", but given the court's reasoning with regard to the single test done (effectively: it's just a single test, so we'll toss it out), why on earth not conduct it?

All in all, I feel there are serious issues to be raised with regard to the Appeal Court's decision concerning the DNA on the knife. I think the chance that the Court of Cassation found the decision  unacceptable is fairly high, and I suspect that, in one way or another, it quashed the ruling on this matter. I do not, however, know what the actual decision will turn out to be. From a formal point of view, the best thing for the new appellant court to do might well be to take up the appeal and disregard the experts' report (and the Appeal Court's reasoning, insofar as it is based on the report) altogether, but as I have said, this leads to practical issues. Conversely, the Court of Cassation might rule only that a new test should be done, and leave it at that. Between these two options there is room for various alternatives.We'll have to wait and see.

A few closing remarks can be made here. Firstly, the Appeal Court did not base its decision with regard to the knife solely on the DNA testing. It also pointed out that issues can be raised with regard to the way the knife was procured (from a drawer in Sollecito's kitchen), with regard to whether it had or had not been washed (starch granules found on the knife seem to indicate it had not been), and with regard to the simple but perplexing question of how the knife (assuming it was used in attacking Kercher) came to be at the Via della Pergola in the first place (after all, it was the original court's assertion that this was not e per-meditated murder, but rather some sort of "game" gone utterly stray). 

Secondly, as set out above, the experts didn't just concern themselves with the actual DNA testing itself. They also pointed out that it could not be established that the sample derived from Kercher's blood. This is true: a specific test carried out to try and establish this turned out negative. This does not in itself mean, however, that it wasn't a blood sample; it simply means that it could not be established as being a blood sample (and the sample may also have originated from Kercher's skin or tissue, which would have been equally meaningful). Finally, the experts pointed to the possibilities of contamination, which is precisely what I'll be discussing in Part Three of this series.


Anonymous said...

Sorry to bring up a completely different point but was it ever shown that Solliceto's knife matched the bloody knife imprint left at the scene? I don't believe that it was. From what I've seen the knife choice from Raffaele's kitchen was purely random.

Andrathion said...

No, I don't the knife matched the print. And yes, there certainly seems to be some randomness involved in the police's choice to take that specific knife from Sollecito's kitchen. As far as I know, it was picked out because it looked "clean", and little more.

Andrathion said...

I should perhaps elaborate a bit. In Kercher's room (on the cover of her mattress)the bloody imprint of a knife was found.This was not, however, left by the "double-DNA" knife (i.e. Sollecito's knife); the print was from a considerably smaller knife.

The print isn't all that meaningful, though. It is clear that the majority of the knife wounds on Kercher's body could not have been made by the double-DNA knife, so if one assumes that the double-DNA knife was used, one would also have to assume that at least one other (and smaller) knife was used also.

In the end, the question of whether the double-DNA knife was used comes down to the DNA test, and, in particular, to whether it can be reliably established that Kercher's DNA was on the knife. If this is not the case, I, for one, feel that the knife should be disregarded as evidence.

If, alternatively, Kercher's DNA was on the knife, then it was used in the attack, along with at least one other knife (the print of which was left on the mattress cover).