Category: DNA and luminol

Wednesday, March 17, 2010

A New York Supreme Court Admits Low Copy Number DNA Testing As Valid

Posted by pat az

[above: the Queens New York Supreme Court]

Cross-posted with an added intro from my own website on Meredith’s case at the kind invitation of TJMK.

The large kitchen knife (image at bottom) found highly cleaned in Sollecito’s apartment was considered by the prosecution (and now by the judges) as the weapon used by Knox and Sollecito to kill Meredith.

Previous posts on the knife on TJMK can be found here. and here, and here, and here, and here, and finally here. 

The knife evidence has been persistently attacked by the defenses and their surrogates on these three fronts.

• First, that it didn’t match the fatal wound on Meredith - although, in fact, it did, perfectly.
• Second, that the DNA charts could match others - but, in fact, there were perfect matches at all points with the DNA of both Knox and Meredith.
• And third, that the sample of Meredith’s was too small for valid results using a new kind of testing which it was claimed would be invalid in US courts.

A ruling in the Queens County New York Supreme Court, released on Feb 8th 2010,  presents difficulties for Knox supporters using this third argument. It is this same type of DNA test that the Queens Supreme court issued its ruling on, a ruling that allowed results from the new DNA test to be admitted into the Queens trial.

The testing is performed on a very tiny amount of DNA material, and it is called Low Copy Number (LCN) DNA testing. The Queens ruling establishes that results from LCN DNA testing can be entered in as evidence, and is the first challenge to LCN DNA testing in a US court. 

While the Queens ruling is only applicable in that jurisdiction, it does establish precedence, and an argument for LCN DNA test results to be accepted at other trials in America.

The DNA test results presented at the Knox trial were key evidence that directly implicated Knox as participating in the murder. Meredith’s DNA was found via LCN DNA testing on a knife found in the apartment of Knox’s boyfriend, and Knox’s DNA was found on the handle of the knife through a regular DNA test.  Based on this, Knox was also found guilty of transferring a murder weapon, which added additional time onto her sentence.

The Queens ruling cites “Frye vs. the US” (1923) to determine criteria for acceptance; Frye “requires the proponent of new or novel scientific techniques to establish by sufficient evidence the general acceptance and reliability of the technique within the relevant scientific community”.

The Queens ruling is that the LCN DNA procedure passes this test, and actually isn’t even a “new or novel” technique; merely a refinement of a generally accepted technique. It further states that while the defense may argue critiques of LCN DNA testing (interpretation issues, transference issues), these arguments “do not affect the admissibility of the evidence for trial purposes pursuant to Frye”.

The Queens Supreme Court is one of 62 in the state of New York, and is similar to circuit courts elsewhere. The highest court in the state of New York is called the “Court of Appeals”.

References here and here. An abridged version of this post was first posted here.

 

Saturday, October 10, 2009

Trial: Further Expert Examinations Denied: The Report From Andrea Vogt

Posted by Peter Quennell

Excerpts from the report of Andrea Vogt (above) in the Seattle P-I.

An Italian jury rejected Amanda Knox’s multiple requests for an independent review of contested evidence Friday, bringing the end in sight to the Seattle student’s contentious murder trial….

Lawyers for Knox and Sollecito, asked the court to approve an independent review of several contested pieces of forensic evidence, most notably the kitchen knife with Knox’s DNA on the handle and what prosecutor’s argue is the Kercher’s on the blade, and a bra clasp with Sollecito’s DNA.

Knox’s lawyers also asked for a review of the luminol-enhanced footprints, the mark on the pillowcase that the prosecution argued was a woman’s shoeprint, but which the defense argues is simply a bloody crease, and several other traces of DNA found in the flat Knox and Kercher shared….

The Kercher family’s attorney, Francesco Maresca of Florence, argued, however, that the court already had plenty of material to review. “We all know that in all trials of this nature there are different analyses of forensic evidence made by the various expert witnesses,” he said. “The court must now consider the seriousness and integrity of the experts’ testimony.”

Prosecutor Manuela Comodi went a step farther, saying while she did not believe a review was necessary, she would she would “almost be pleased” to see the results with regard to the prosecution’s footprint expert analysis.

The eight-member jury, which includes two professional judges, flatly rejected all defense requests at 9:30 p.m. after deliberating just under two hours.

Immediately after the judge’s announcement, Sollecito bowed his head and briefly wept, as lawyers began haggling over court dates for closing arguments.

Knox glanced worriedly at her lawyers, who patted her on the back and insisted confidently after the hearing that the outcome was not unexpected, nor necessarily negative for their client…

“This doesn’t change anything,” said Knox’s Perugian attorney, Luciano Ghirga. “We wanted to clarify the evidence, but obviously the judge doesn’t feel he needs additional information. We are ready to argue.”

The judge was careful to note that the jury’s decision did not indicate a presumption of guilt and left open the possibility that the court could call for additional review of evidence after closing arguments and before a verdict.

Nonetheless many court observers expressed surprise at the fact that the jury chose to not review even a single element of the controversial forensic evidence. For Knox, however, the complete rejection of a third-party review could have a silver lining—effectively positioning her better for an eventual appeal.

Our legal watchers doubt the validity of that last remark - that somehow the judges and the jury have messed up here, and that this is a get-out-of-jail-free card for Knox’s and Sollecito’s appeals.

They note that Italy has a “smart jury” system which is encouraged to take a very broad birds-eye view of the case. The multi-alibis testimony and the mobile-phone testimony and the eye-witness testimony and the various mixed-blood traces and the various bloody footprints are considered almost impossible to account for if the defendants are in fact not guilty. The DNA on the knife and the bra-clasp are not make-or-break issues in this case and never were.

The sleeper in this trial of course as in the Rudy Guede trial is the huge and very detailed report that the judges must prepare and release within three months of their verdict. The astounding level of profesionalism of those reports - unique in the law world - leaves American lawyers in real awe.  In the case of Guede, the report by Judge Micheli was absolutely damning.

If the verdict here also is guilty, those unconvinced by that report will probably all fit neatly into one Volkswagen.

Trial: Further Expert Examinations Denied - The Report From Nick Pisa

Posted by Peter Quennell

Excerpts from Nick Pisa’s report in the UK’s Daily Mail.

A judge last night rejected defence requests for an independent review of evidence in the Meredith Kercher murder case.

The decision means that a verdict in the trial will come by early December as an independent review could have taken up to a month delaying the decision….

Yesterday lawyers for Knox and Sollecito argued that the review should be held because of errors in the police investigation and the way evidence was collected.

Key to the case is a 30cm black handled kitchen knife on which DNA from Knox was found on the handle and that of Meredith on the blade.

Prosecutors say the knife, which was found in the kitchen of Sollecito’s flat, is compatible with the murder weapon - which has never been found.

Knox’s lawyer Carlo Della Vedova said that too many discrepancies had emerged in the examination of the knife by forensic scientists….

Sollecito’s lawyers had also asked for a review of a bloodied bra clasp found at the scene which had his DNA on it.

They pointed out that the clasp had been found during an initial police search in one point and then ‘lost’ for six weeks before being found else where in the room….

Prosecutor Giuliano Mignini had argued that: ‘There is no need for a review as the evidence was gathered in a very professional way by qualified persons.’

In his ruling judge Massei said: ‘The court has heard from several consultants who have brought several elements and which rule out the need for any further proof.’...

As the judge read out his decision Knox, who earlier had been laughing and joking with guards, closed her eyes and looked upwards.

Sollecito rubbed his eyes and was in tears as the decision would seem to indicate the court has already made up its mind over their guilt.

Friday, September 18, 2009

Trial: Defense Expert Tries To Claim Sollecito-Sized Footprint Is Guede’s

Posted by Peter Quennell

Click above for the Daily Express’s full report. The relevant section:

A bloody footprint found at the house where a British student was killed in Italy was wrongly attributed to one of the defendants in the case, a forensic expert has testified at the murder trial.

The footprint was found on a bathroom rug in the house in Perugia where Meredith Kercher was killed in November 2007.

Prosecutors have attributed it to Raffaele Sollecito, an Italian who is on trial on murder charges with Amanda Knox, his girlfriend at the time. Both defendants deny wrongdoing.

In his testimony, expert Francesco Vinci compared detailed pictures of the footprint on the rug with images of Sollecito’s feet, arguing that the sizes and shapes “absolutely don’t match”.

“Differences, one by one, can be seen,” said Vinci, who is a witness for Sollecito’s defence.

According to Vinci, the footprint is “compatible” with the foot of a third man, Rudy Hermann Guede, who was convicted in a separate trial last year and sentenced to 30 years in prison.

In effect then, the claim is that Guede was participating with bare feet in the cleanup of the crime scene some time after the death of Meredith - although precisely what he cleaned up is unclear, as strong evidence of his presence remains.

Like many of the defense’s attempts at rebuttals, this sounds to us like a tragedy that is now playing out as farce.

In one of his clinically precise powerpoints Kermit already refuted this claim

 

Monday, September 14, 2009

Trial: Judge Massei Rejects Feeble Defense Bid To Throw Out DNA Evidence

Posted by Peter Quennell

So the trial has resumed, amid conjecture that it might last for additional months if the DNA evidence is to be independently assessed.

That possibility seems to have disappeared in a hurry. Raffaele Sollecito’s lawyer Giulia Buongiorno (above) made a request that some of the DNA evidence be thrown out.

Judge Massei speedily and very firmly ruled against. He clearly appears to consider the evidence and the procedures that were followed to be sound.

First, the DNA analyses in question were performed in the presence of defense experts, who did not make any comment at the time. And second, no substantive DNA information was wrongly withheld from the defenses and so the defendants’ rights were not violated.

[Judge Massei] added that relevant documents had been made available a month-and-a-half ago, suggesting that defence teams had enough time to review the DNA findings.

Our takes on the DNA component of the case (which our legal watchers say is far from being make-or-break evidence in this case) can all be found here.

Thursday, July 23, 2009

Case For The Prosecution: #2 The Tough Footprint Evidence

Posted by The Machine

1. Preamble

This series is a summary of the prosecution’s case in five parts, with a commentary on matters of key significance.

The material has been reordered so that evidence presented at several points in the trial can be described in one post here. Sources used are the many published reports and some transcripts made of the testimony. The first post, below, was on the formidable DNA evidence.

In this post we now elaborate the footprint evidence, some of which is easily visible and some of which is only apparent with the use of luminol.

We reported what happened in the court here and here.

Kermit in his Powerpoint series provided us with accurate prior analysis and post analysis of these flootprints and shoeprints, and Kermit also presented a Powerpoint map of the cottage.

2. About luminol

Luminol is a chemical that reacts with the microscopic particles of iron in the blood if a partial but incomplete attempt has been made to clean a bloodstain away.

The blood traces glow a bright blue quite fleetingly in the dark under luminol, just long enough to allow forensic investigators to measure and photograph it.

Luminol evidence can be among the most compelling. If bloodstains show up under luminol, but not to the naked eye, then it is almost a complete certainty that a crime-scene clean-up has been attempted.

Lorenzo Rinaldi is the director of the print-identity division of Italy’s scientific police, the Italian equivalent of Scotland Yard or the FBI. He testified that one visible and three luminol-revealed footprints and a visible shoeprint belonged to the present two defendants, Amanda Knox and Raffaele Sollecito. (Another shoeprint belonged to Guede, convicted last October.)

3. Evidence Against Amanda Knox

Amanda Knox’s footprints were found set in Meredith’s blood in two places in the hallway of the new wing of Meredith’s house. . One print was exiting her own room, and one print was outside Meredith’s room, facing into the room. These bloody footprints were only revealed under luminol.

The fact that there was an absence of any visible bloody footprints from Meredith’s room where Meredith’s blood was to the visible bloody footprint on the blue bathmat in the bathroom that Meredith and Knox shared strongly indicates that some prints were successfully cleaned away altogether.

A woman’s bloody shoeprint which matched Amanda Knox’s foot size was found on a pillow under Meredith’s body. Barbie Nadeau noted the significance of this evidence on The Daily Beast website:

“When the judge asked Rinaldi the size of an unidentified bloody shoeprint found on the pillow below Kercher’s body, he responded, “Between 36 and 38.” The judge then asked Rinaldi what size shoe Knox wears. “The Skecher shoe we sequestered belonging to Amanda Knox corresponds with size 37.”

The significance of the woman’s bloody shoeprint in Meredith’s room is considerable. By itself it debunks the myth that some had propagated for a while, that Rudy Guede acted alone. The bloody shoeprint was incompatible with Meredith’s shoe size.

4. Raffaele Sollecito

Two bloody footprints were attributed to Raffaele Sollecito. One of them was revealed by luminol in the hallway, and the other one was easily visible to the naked eye on the blue bathmat in Meredith’s and Knox’s shared bathroom.

Lorenzo Rinaldi excluded the possibility that the bloody footprint on the blue bathmat was the right size or shape to belong to Knox or Guede instead of Sollecito: “You can see clearly that this bloody footprint on the rug does not belong to Mr. Guede, but you can see that it is compatible with Sollecito.”

Andrea Vogt’s report for the Seattle Post-Intelligencer shows just how meticulous and painstakingly detailed the analysis of the bloody footprints was:

“All the elements are compatible with Mr. Sollecito’s foot,” Rinaldi said, pointing with a red laser to a millimeter-by-millimeter analysis of Sollecito’s footprint projected onto a big-screen in the courtroom. He used similar methods to exclude that the footprint on the bath mat could possibly be Guede’s or Knox’s.

“Those bare footprints cannot be mine,” said Sollecito in a spontaneous statement…. But the next witness, another print expert, again confirmed Rinaldi’s testimony, that the print, which only shows the top half of the foot, matches the precise characteristics of Sollecito’s foot….

Rinaldi’s detailed PPT described methods of image analysis, metric and grid measurement of the ball, toe, heel and arch, as well the particular characteristics of the footprints and shoeprints as well as the actual shoes and feet of Knox, Sollecito and Guede. The three suspects gave their footprints and fingerprints at police headquarters.”

Another print expert also testified that the bloody footprint on the blue bathmat matched the precise characteristics of Sollecito’s foot.

Amanda Knox’s lawyer, Luciano Ghirga, asked Dr. Stefanoni to confirm that other substances like bleach or fruit juice can also react to luminol.

Dr. Stefanoni acknowledged that they do, but pointed out that biologists who work regularly on crime scenes distinguish easily between the bright blue glow of a blood trace and the much fainter glow from other reactive substances

Tuesday, July 21, 2009

Case For The Prosecution: #1 The DNA Evidence

Posted by The Machine

[Above: Prosecutor Manuela Comodi, click for larger image]

1. Preamble

Nearly 200 hours over 23 days.

That is how long the prosecution took to present its voluminous case against Amanda Knox and Raffaele Sollecito, including time taken by the defense teams to conduct cross-examinations.

This series is a summary of the prosecution’s case in five parts, with a commentary on matters of key significance. The material has been reordered so that for example the DNA evidence presented at several points in the trial can all be described in one post here.

Sources used are the many published reports and some transcripts made of the testimony. All the main witnesses will be named in this series with a brief mention of who they are and their qualifications.

Two past posts that may aid in understanding the DNA testimony are Nicki’s post here and Fiori’s post here. All past DNA posts can be found in this area. 

2. The Large Double DNA Kitchen Knife

The double DNA knife is the knife that was sequestered from Sollecito’s apartment. Although there was an imprint of another knife at the scene, and one defense expert argued that there may have been yet another, it remains plausible that this is the weapon that was used to murder Meredith.

Dr. Patrizia Stefanoni was the leader of the forensic team from Rome that carried out all the forensic collections at Meredith’s house.  She testified unequivocally about the knife. A small sample of Meredith’s DNA was found to be in a groove on the blade, and Amanda Knox’s DNA was found to be on the handle.

Dr. Stefanoni noted that there were peculiar diagonal scrapes on the knife blade, which suggested that the knife had been vigorously cleaned.

Both Dr. Renato Biondo, the head of the DNA Unit of the scientific police, and the Kerchers’ own DNA expert, Professor Francesca Torricelli, provided independent confirmation that this forensic finding is accurate and reliable.

The defence teams’ forensic experts are not disputing that Meredith’s DNA was on the blade of the knife. Instead they are arguing that the knife was somehow contaminated for the DNA to actually be there.

Dr Stefanoni has firmly excluded this possibility of contamination in transit or in the laboratory. She testified that there hasn’t been a single instance of contamination in her laboratory for at least the last seven years, and every precaution was taken here to ensure that different traces were not mixed.

A police officer who led a search of Sollecito’s apartment added weight to the prosecution’s assertion that the double DNA knife had been cleaned with bleach. He testified that he had been struck by “the powerful smell of bleach”. 

When Raffaele Sollecito heard that the scientific police had found Meredith’s DNA on the double DNA knife in his apartment, he did not deny the possibility of the DNA being there.

Instead he made a claim about accidentally pricking Meredith’s hand whilst cooking at his apartment. “The fact that Meredith’s DNA is on my kitchen knife is because once, when we were all cooking together, I accidentally pricked her hand.’‘

However Meredith had never been to Sollecito’s apartment and so it seems Sollecito could not have accidentally pricked her hand there whilst he was cooking. In attempting to explain the presence of Meredith’s DNA on the blade, he did so in a way easily disproved and seemed to further implicate Amanda Knox and himself.

3. Sollecito’s DNA On Meredith’s Bra Clasp

An abundant amount of Raffaele Sollecito’s DNA was found on Meredith’s bra clasp, and Dr. Stefanoni has excluded the possibility of any contamination.

This is the bra clasp that was collected some weeks after the first forensic collection and it was conceded that it should have been collected earlier. It was also argued that valid DNA evidence in other cases is often collected weeks or months or even years after the crime when a suspect object is unearthed.

Sollecito’s lawyer Ms Buongiorno is perhaps not surprisingly claiming that this bra clasp was also contaminated in the laboratory. The problem for them is to explain precisely where such an abundant amount of Sollecito’s DNA could have come from, and how it was so firmly imprinted.

The only other instance of Sollecito’s DNA at the cottage was found on a cigarette butt in the kitchen, seemingly an unlikely source at best.

It would seem unlikely that the judges and jury will conclude that the bra clasp was contaminated in a strictly controlled laboratory where Dr. Stefanoni follows rigorous laboratory procedures.  She is an internationally renowned and very experienced forensic expert and was part of a Disaster Investigations Team which identified disaster victims via their DNA.

Alberto Intini is the head of the Italian police forensic science unit. Andrea Vogt reported as follows in the Seattle Post-Intelligencer on Mr Intini’s testimony about the possibility or otherwise of contamination:

“Alberto Intini maintained that the crime scene had not been contaminated and pointed out that laboratory testing revealed none of the investigators’ prints or biological traces. Mr Intini said “In fact, it is the results that tell you if it was done correctly, and I can tell you that in this investigation there was not even one trace of any of our operators.”

He also pointed out that unless contamination has been proved, it does not exist. “It is possible in the abstract that there could have been contamination, but until this is proved, it does not exist.”

The prosecution demonstrated on the final full day of testimony that Meredith’s bra was actually removed with a knife some time after she had been killed.

Judge Paolo Micheli presided over the fast-track trial of Rudy Guede and committed Sollecito and Knox to trial. In looking at the identical evidence he asked “Who had a reason to come back, cut off Meredith’s bra, and move her body some time later?”

The present judges and jury might conclude differently, but Judge Micheli concluded that it would only have been done by someone who knew about Meredith’s death and had an interest in arranging the scene in Meredith’s room to point away from themselves. He discounted Rudy Guede, who apparently went home, cleaned himself up, and then was seen out on the town.

4. Knox Blood With Meredith’s

There were five instances of Amanda Knox’s blood or DNA mixed with Meredith’s blood in three different locations in the cottage in Via della Pergola: the bathroom, the hallway, and Filomena’s bedroom.

Amanda Knox’s blood was found mingled with Meredith’s blood in three places in the bathroom: on the ledge of the basin, on the bidet, and on a box of Q Tips cotton swabs.

Dr. Stefanoni testified that it would have been “strange” that three traces of blood with both Meredith’s and Amanda Knox’s DNA would have been left at different times.

Barbie Nadeau in Newsweek pointed out a reason why the blood stains must have been left on the night of the murder:

“Legal experts who follow this case have suggested that blood evidence cannot be dated and therefore could have been left weeks before the murder. But when Knox testified in her own defense in June, she conceded that there was no blood in the bathroom the day before the murder, effectively dating those blood stains to that night.”

Perhaps Knox had a bloody earring piercing, and maybe a drop landed on a drop of Meredith’s blood. But in three different places? Perhaps it is not surprising that the defence lawyers have not brought up the subject of the mixed DNA in the bathroom in their part of the trial.

Meredith’s blood was found on the top part of the light switch in the bathroom she shared with Amanda Knox. This suggests that it was deposited there when the light was switched on. Meredith’s blood was also found on the toilet lid. There were no DNA or other physical traces of Rudy Guede in that bathroom.

Knox’s DNA and Meredith’s DNA was also found mixed together in a bloody footprint in the hallway of the new wing of the house.

A mixture of Knox’s DNA and Meredith’s blood was also found in Filomena’s room. This seems to be compelling evidence because Knox had never claimed she entered Filomena’s room when she checked the cottage. This room was the scene of the alleged break-in, and there were glass fragments on the floor.

Meredith’s blood had been cleaned up in this room, but it was nevertheless revealed by luminol.

Barbie Nadeau concludes in a Daily Beast report that the mixture of Knox’s DNA and Meredith’s blood in Filomena’s room seems more incriminating than the double DNA knife:

“But perhaps more damning even than the knife was Stefanoni’s testimony that a mix of Knox’s DNA and Kercher’s blood was found on the floor in the bedroom of a third roommate, Filomena Romanelli.”

Saturday, July 18, 2009

Trial: ASCA Wraps Up For Final Day Before The Trial Breaks To 14 September

Posted by Peter Quennell

Click above for ASCA’s report in Italian. A quick translation of the main points:

Adriano Tagliabracci, a DNA consultant for the defense of Raffaele Sollecito, testified to the contamination and therefore the unreliability of one of the DNA finds that the prosecution considered particularly important.

According to the expert, the handling of the hook of Meredith’s bra where Sollecito’s DNA was claimed by prosecution experts to have been identified followed incorrect procedures, both in the collection and in the final analysis and interpretation. For this reason, the finding is not reliable.

The work of the forensic experts, moreover, in Tagliabracci’s opinion, was not in line with what is recommended by international bodies, starting with the long interval of time, 47 days, between the discovery of the bra hook on November 2, under the pillow which had supported the victim, and its collection for evidence on December 18 from under a mat.

In this period, three visits to the house were made by an unknown number of crime-scene processors who used many unspecified procedures which might have created a situation where the possibility of contamination was increased..

Given that the DNA of Sollecito was derived from epithelial cells, there is a firm possibility that, contrary to the claims by the police and Patrizia Stefanoni, the chief scientific expert for the prosecution, the DNA could have been placed on the bra hook during those visits.

The bra hook in question was made available in the courtroom today in a plastic evidence envelope.

An excellent prior analysis of this piece of evidence was posted by our DNA poster Nicki on 29 May here. Nicki, an expert in the field, was totally disbelieving that the DNA got on that hook by accident.

She concluded that Sollecito must have handled Meredith’s bra hook - and moreover, with a very firm grip.

Saturday, July 11, 2009

It Is The Jury That Ultimately Matters: How They May Be Seeing The DNA Here

Posted by Fiori

Example of well-equipped Italian DNA lab


Ciao! Posting again from Florence.

Nicki and Kermit have already done amazing work here and here in explaining the hard facts of the DNA evidence.

This post is about perceptions and about what the judges and jury might - might - now be thinking, now that those facts are presented and some of them contested.

DNA evidence is notoriously hard to present and argue before a jury. It is not only in the trial against Amanda and Rafaelle that one finds problems, ambiguities and different interpretations of the validity and reliability of DNA, this is the same in many criminal trials.

Standardization of DNA testing procedures got an enormous boost by the unforeseen “accident” in the OJ Simpson’s trial, where the jury, according to all scientific authorities, failed to recognize the DNA evidence properly. Since than the overall public understanding of DNA has been increasing, and jurors and others agents have earned a familiarity with handling DNA in criminal trials. All this suggests that it is generally getting easier for jurors to understand when and how DNA is significant in a trial.

It is of great importance to underline that the jury is the crux of every case: No matter what Dr. Stefanoni knows and how she may have handled the DNA samples, it is the jury, this particular selection of individuals, which has to make sense of the testimonies, and form an understanding of what the DNA samples tells about the murder of Meredith and the possibly involvement of Amanda and Rafaelle (and Rudy). I emphasize this:

• Jurors are not a scientific committee, and the way which a jury understands DNA differs considerably from a professional, scientific understanding of DNA


• Jurors’ understanding of DNA is highly situational; i.e. it is heavily influenced by how, when and by whom DNA material is presented during the trial


• Jurors build their comprehension from context, meaning that a jury does not base their understanding upon systematically selected information about DNA, but forms an opinion based upon an interrelation of scientifically based information and the circumstances of the present case

Findings from the US and UK system of justice

What characterizes jurors’ judgments of DNA material in criminal trials? It is usual to expect that the more scientifically complex a piece of evidence is, the more difficult is it for a jury to comprehend, but from studies in UK, US and Australia several other things are known:

• Among jurors who were aware of DNA profiling evidence before their participation in the researched trials, expectations for the evidence in determining the guilt or innocence of an accused were high, and these expectations were largely confirmed by the jury members experiences of the trial itself.


• Juror comprehension of DNA evidence is not solely dependent on the scientific complexity of the evidence. If the evidence is presented clearly in court, if the expert testimony is consistent, if the defences do not present contrary interpretations of the DNA evidence, and the case is otherwise circumstantial, then jurors seem to manage a fair understanding of the science and weight it significantly in case material.


• The strength of the defence challenge may depend on the coherence and grounding of an alternative explanation or conclusion drawn from the DNA. Meaning: it is NOT generally so, that IF a piece of DNA evidence is NOT contradicted by the defence, then it is easier for a jury to comprehend DNA evidence. HOW a jury interprets DNA evidence depends upon the context of the PRESENTATION of the evidence.

Research into US trials reports that jurors mostly are much more skeptical toward DNA evidence than statistics gives reason for. The jurors often “incorrectly aggregate separately presented probabilities and afford probabilistic evidence less weight than would be expected [by experts]” and “their background beliefs about the possibility of laboratory errors and intentional tampering affects the weight participants afford a DNA match report.”

A juror’s interpretation of expert testimonies is highly influenced by the credibility they assign to the legal and scientific system; i.e. all the institutions involved in a trial: the police, the legal system, the forensic police, and scientific institutions in general.

The point made here is that jurors and legal systems have “historical memory” so the result of one trial influences the outcome of another:  Thus, it is possibly that the OJ Simpson case and the many faulty convictions based upon DNA “˜evidence’ has produced a overt negative attitude towards DNA in the US, which is not to be expected to be the same in Italy.

Another conclusion, also from research within the US: Cognitive errors favoring the defence were more prevalent than errors ones favoring the prosecution. This piece of research examines how jurors’ evaluates that part of the DNA testimony which involves probabilities and statistics. And as this touches upon core questions brought up in the case against Amanda and Rafaelle, I will quote in length from the paper.

The paper, which studies the outcome of several (murder) trials - concludes that “some jurors showed susceptibility to classic (defence) fallacies in interpreting conditional probabilities, and the jurors as a group were not overwhelmed by testimony from a prosecution expert that “˜more than 99.98% of all Caucasians would be excluded’ by the DNA match.
Most jurors accepted a defence criticism of this computation. Moreover, it appears that many jurors were inclined to agree with the defendant’s overstated argument that because dozens of men in the area might have DNA types consistent with those of the robber, the match with the defendant’s DNA was worthless. A smaller number seemed to commit what has been called the “˜prosecutor’s fallacy.’ These jurors did muddle up the proportion of the general population that would be excluded by a DNA test, and the probability that the defendant was the source of the crime-scene DNA.
On balance, these findings do not indicate that jurors generally were unduly impressed by the prosecution’s DNA evidence. Consequently, our results challenge the legal argument that DNA evidence should be excluded because jurors are prone to overvalue such evidence.”

So, measured in relation to the expert testimony actually given in court, this research found that jurors made misunderstandings and misinterpretations biased BOTH ways. The research did not find jurors to be “˜unduly impressed’ by prosecutions experts testimony, but instead being “˜susceptible’ in favour of the defence. 

But other research indicates that some jurors are being too impressed by the DNA evidence or mislead by the statistics presented in court.

Research from UK and US, states that “a number of convictions which have relied on DNA evidence have been overturned on appeal on the basis of misdirection of the jury regarding the statistical basis of the test and its results. In particular, juries are often awe-struck by the enormous values of random occurrence ratio with which they are presented by the prosecution experts. The factual significance of these large numbers is often misunderstood and misrepresented by barristers and judges, leading to unsafe convictions.”

Then, not only the jurors, but the legal actors more widely have problems with understanding how the statistical dimensions of DNA evidence works. The point of the statistics is, that identifying the DNA markers can be misleading if identification of the suspect occurs on behalf of “˜random occurrence ratios’ ““ i.e. the suspect is identified in random by her DNA (similar to how fingerprint identification works).

Identification on behalf of DNA must relate to the demography of the area where the crime took place, as well as the family background of the suspect. Meaning that statistics can be misleading if identification is not supported by additional information (where much exists in the trial against Amanda and Rafaelle). Dr. Stefanoni has repeatedly argued this point in court, explaining why Amanda’s DNA is Amanda’s, and Rafaelle’s DNA is Rafaelle’s, and not a “˜random’ person, like an unknown friend of Rudy’s.

From research into the working of the US and the UK legal systems, it must be clear that most of the news-reports from the US about the murder of Meredith Kercher tend to reinforce a common deficit in knowledge on how to interpret DNA evidence. A shame that.

Also worth mentioning is that the OJ Simpson trial is not the only one where “˜scientifically’ obvious DNA evidence have been disregarded by a jury; this also seen in cases where there presented a lot of other circumstantial evidence supporting the DNA material.

And that different interpretation (prosecution and defence) of DNA material does not in itself blur jurors comprehension and prevent an unanimous understanding of the significance. Contrary, controversies over DNA can serve to clarify a juror’s understanding of DNA.

Example of well-equipped Italian DNA lab

Likely differences under the Italian system of justice

These results from research into the US/UK type of legal system should be discussed in relation to the working of the Italian system. And there are, in this perspective, significant differences.

In Italy, a jury consists of 6 lay persons and 2 professional judges. It is highly likely that the participation of 2 professional judges influences how the jury perceives and discusses DNA and other complex scientific matters. The above quoted research into fallacies of comprehending DNA evidence can only support the view that it is a strength of the Italian system that professional judges are represented in the jury.

Also, the Italian trial system, where parts of evidence are presented and assessed by multiple judges in many pre-trial hearings, also marks a difference vis a vis the US system. Every (pre-) trial adds to jurors possibility to comprehend DNA material correct (”˜correct’ in relation to understanding what is actually testified in court, not “˜correct’ in relation to assessing the significance of the DNA material as evidence).

As referred to above, pre-trial experiences also influences how jurors interpret DNA testimony.

Then education, schools and general cultural education (”˜bildung’ in German), cultural habits (for example if criminal trials are broadcast or not, and if they are watched widely or not) will without doubt influence how jurors comprehend DNA evidence. And of course so will criteria used by the court for selecting the actual jury influence the outcome; for example if it was considered important that jury members demonstrated ability to understand complex scientific arguments.

Generally, European comparative test shows that primary education in Italy are in the upper middle, and Italy has very good universities and strong academic traditions, and ““ not the least - a long and proud tradition in science from Leonardo da Vinci and onwards.

These conditions will influence the jury’s assessment of DNA evidence presented in the trial against Amanda and Rafaelle, and we can expect that the jury will demonstrate a fairly accurate understanding of the different testimonies from (a.o.) Dr.Stefanoni and Dr.Torre, and a fairly accurate understanding of DNA technology. Though, how the jury will make sense of the scientific facts in the actual circumstances (what it tells about who murdered Meredith) are not obvious.

Scientific references to the quoted papers are listed in my comment below.

Wednesday, July 08, 2009

Defense Experts Testimony: Daily Beast Posts The Most Detailed Report In English

Posted by Peter Quennell

Click above for the report by Barbie Nadeau on the disputatious knife and DNA-handling evidence..

[Coroner Torre and genetic expert Gino] testified that “Exhibit 36,” a knife found in Sollecito’s apartment with Knox’s DNA on the handle and Kercher’s on the blade, cannot be the murder weapon. Torre showed pictures of Kercher’s wounds to the jury, then used a mannequin to demonstrate that this knife was too big to make two of the wounds in Kercher’s neck. He conceded that a third larger wound could have been made with the knife, but said it was more likely it was made by twisting a smaller knife….

Although Torre and Gino, who did not examine Kercher’s body, both testified that they saw no evidence that more than one person was involved in her murder, countless prosecution witnesses, including two coroners who did examine Kercher’s body, testified that the 47 cuts and bruises indicated that “more than two hands” were at work.