The Amanda Knox verdict - no holiday for the Italian criminal justice system

In this article, first published on the Halsbury's Law Exchange blog, Felicity Gerry looks at the fallout from the Amanda Knox appeal verdict

No surprise last week when a jury in Perugia overturned the murder conviction of Amanda Knox and her former boyfriend Raffaele Sollecito for the killing of Meredith Kercher four years ago. The DNA evidence was obviously flawed and the confession was worthless. The case is a timely reminder that criminal trials are about proof, not opinion.

Whilst there is no doubt as to the probative value of a full profile DNA match, low template DNA and partial profile DNA are also admissible in certain circumstances but need to be considered with care alongside the other evidence. The danger remains that, if not properly collected, stored, analysed and presented, any jury will give undue weight to scientific evidence resulting in incorrect results in criminal trials as all parties (victims and defendants) found to their cost in Italy. The whole process was bogged down in a fascination for Amanda Knox's sex life rather than the evidence for murder.

On 7 August 2007, David Reed and Terence Reed were convicted at Teesside Crown Court for the murder of Peter Hoe by multiple stabbing. The evidence against them was both motive and opportunity. Telephone and witness evidence put them in the area at the time of the killing and there was a relevant background to the incident. The defence case was one of alibi.

Low quantities of DNA in relation to each defendant were found on two pieces of plastic from knife handles found near Peter Hoe's body. The components of the DNA had been revealed using the Low Copy Number (LCN) process. They were not from blood or other identifiable biological material, but simply cellular material that had been transferred to the pieces of plastic. There was no real dispute with a defence assertion that the cellular material could have been transferred from another source but the prosecution expert thought this unlikely. She gave evidence that in her opinion the DNA got there by handling. The material had been properly collected and stored.

In Italy, an Italian appellate court judge ruled that the prosecutors used substandard methods and contaminated the evidence. Prosecutors had alleged that evidence of Amanda Knox's blood was found on a knife used to carry out the killing but the microscopic amounts of DNA found on the knife as well as on a bra clasp, were shown to be of little value after a report from independent experts criticised the Perugia police's handling and analysis of the materials.

DNA from a co-accused who pleaded guilty was found at the scene which made for a simple case against one man. However, the Italian authorities chose to pursue Amanda Knox and her then boyfriend based on weak and flawed evidence, a seemingly unreliable confession, evidence from a co-accused with an agenda and theoretical motives that created a worldwide scandal.

US forensic experts reviewed the DNA evidence in the Knox case and outlined their concerns that police mishandled their collection of samples. Oddly, this evidence was not used in the original trial but later formed the basis of the appeal. It was said to be a typical kitchen knife, found in a kitchen drawer with other knives, not well cleaned and not used as a murder weapon. In addition, according to Discovery News; the Italian prosecutors used a DNA detection limit far below that of the independent US experts or the FBI in determining the presence of blood DNA on the blade, which made contamination a much more likely source of the genetic material. Similar issues arose in relation to the bra clasp along with problems with storage.

There was strong evidence against Rudy Guede, who was separately convicted of Meredith Kercher's murder and is serving 16 years in prison and weak evidence against the two people now notoriously acquitted. So, how did this happen?

The LCN process allows for the analysis of very low quantities of DNA. A tiny sample is recovered and copied then each component seen is given a number. It is as if a drop is turned into a pond then the experts go fishing for components and try to agree which components are present. Each dip might bring up a different component but the ones that appear the most are components which, according to expert opinion, can be included in the sample and, in some cases, given a statistic as to how many other people might be likely to have the same DNA.

Even where such a statistic cannot be given, the Court of Appeal here has said that such low quantities could be used to say that the defendant was not excluded from the potential pool even though it could not be said how many other people could be included.

Neil Garmson was convicted at Stafford Crown Court on 20 August 2007 of kidnap, rape and sexual assault which related to incidents that had occurred in April 2005 and March 2006. In 2005, the complainant and her partner had gone by car to a country park, a man tapped on the window then got into the car and demanded that he be driven to Newport. He ordered the partner out of the car, forced the woman to drive to a lay by where he raped her. Afterwards she was ordered to drop him off in Newport. Garmson was identified by DNA taken in the 2006 incident.

In March 2006 a man forced himself into the back of a car in which a young woman was sitting. In the front passenger seat was another woman. The driver was a man. The perpetrator threatened them with a knife, demanded money and directed the man where to drive. He then sexually assaulted the woman in the back seat. Both women managed to escape. The driver was ordered to drop the man at a particular location. Garmson was subsequently identified by DNA taken from the lip of the victim. The DNA was merely a few components (known as a partial profile) but the Court of Appeal concluded it was admissible as it was not the only evidence. The prosecution also relied on the similarity of the attacks, fibres from the car which matched a jumper recovered from Garmson's home, his knowledge of the area and that the drop off was near his mother's house along with relevant comments he made on arrest.

So, as has been described, the Court of Appeal's judgment allows for low samples of DNA and partial profiles to be admissible in a criminal trial even where there is only a part profile or indeed a very low quantity and the accuracy of the findings depends on expert opinion and/ or there is a possibility of transfer. The Court of Appeal put no limit on how few components can be considered as useful but made it clear there should be other evidence.

The analysis of a crime scene sample, even in relation to DNA, is not necessarily an exact science. The admissibility of a complex mix of DNA from more than one person was considered in R v Ishaq at Leicester Crown Court in January 2010 which I defended.

This was a cold case gang rape from 2000 where there was DNA evidence which could prove presence but some of which was also consistent with transfer. In addition, experts eventually agreed on the day of trial that the possibility of a person other than the defendant being responsible could not be excluded as the computer had given an indication of components present in a partial profile, which had initially been discounted by the Forensic Science Service (FSS). At least one of those components was not in the profile taken from Mr Ishaq in 2008 and could not be attributed to others implicated or convicted suggesting someone else with some corresponding DNA components could have been responsible and not Mr Ishaq. He was acquitted.

The finding of DNA at a crime scene is a useful tool in proving the identity of the offender particularly in serious sexual offences and murder. In all of the above cases the defendants suggested they had an alibi for the events. The DNA evidence was used to put them at the scene and therefore to prove the commission of the crime. However, as few as four components were used in relation to Garmson, the possibility of transfer was accepted in the Reed case and Mr Ishaq's case made it plain that the FSS experts will exclude components which the computer indicates are present and which could exonerate a suspect. These cases are not easy. All the more reason to connect an alleged killer by other reliable evidence then supported by DNA evidence rather than the other way round. It very much seems as though the Italian authorities built a theoretical case around flawed scientific findings.

Much opinion was expressed on the Italian streets in both directions. There is no doubt, however, that the whole business has been skewed by PR and media intervention so that what should be calm and unemotional legal proceedings have got completely out of hand resulting in notoriety for the accused and devastation for a family already suffering loss.

It has been a poor advert for the Italian criminal justice system. The delays, posturing and lack of understanding leave a lot to be desired. There is obviously massive tension between the judiciary and executive and this case will have a long lasting effect on a legal system that appears close to collapse.

It's food for thought in the current legal climate in this country. I hope we are a long way from a situation where the only way to acquittal will not be on the evidence but for those with financial support and a good PR machine. In the meantime, the Italians have no choice but to get their system in order before another car crash of a trial hits the world's front pages.

Felicity Gerry is a criminal barrister and a contributor to the Halsbury's Law Exchange blog. Click here to follow the Halsbury's Law Exchange on Twitter and click here to follow Felicity.

For more, see A question of guilt by Herbert Smith partner Robert Hunter.