It is without a doubt that mixed DNA profiles are one of the most complex areas of Forensic DNA analysis.  The method of statistical analysis used for evaluating mixed DNA profiles is the ‘likelihood ratio’.  The likelihood ratio looks at the probability of the evidence if the prosecution hypothesis is true, versus the probability of the evidence if the defence hypothesis is true.  The result will usually be reported something like this:  the evidence is 4000 times more likely if the DNA originates from the defendant and Mr X, than if it originated from Mr X and an unknown individual.

Until recently, these likelihood ratios were calculated either by hand; or using a basic spreadsheet; or in house developed piece of software.  However, criticism was often made of scientists’ ability to statistically interpret mixed DNA profiles, as the method involved some elements of subjectivity.  The scientist had to determine which peaks were ‘real’ and which weren’t, as well as determining the number of contributors to the profile.  They also would use subjective determination to rule out certain combinations of DNA.  This all meant that if you provide ten different scientists the same DNA profile, and you could end up with ten different answers.

A group of scientists in Australia and New Zealand decided to tackle this issue head on, and STRmix ™ was born.  STRmix ™ is a software tool which uses mathematical modelling to conduct statistical analyses of mixed DNA profiles.  And it can do a great job – there’s no doubt about that.  But, there are some downsides.

• The mathematical modelling itself is very complex.  I highly doubt most forensic DNA analysts understand it.  This is very different to the old ‘binary method’ of calculating a likelihood, which was very transparent.
• The software cannot determine the number of contributors – the scientist must do this, meaning that subjectivity is still being used.
• Similarly, if a scientist does not like a ‘peak’ in the profile, they can remove it before running the profile through the software

So, our question is, does this software solve the problem that it set out to?

In many instances, yes it does.  For a start, STRmix ™ reduces the time it takes to deconvolute a mixed DNA profile down from hours, to minutes.  This is a great advancement as the majority of crime DNA profiles obtained nowadays are mixed DNA profiles (due to recent increased sensitivity of DNA analysis).  And the modelling itself has been shown to be robust, thought-out trials involving thousands of DNA profiles.

However, this is under the assumption that the profile itself is a) suitable for analysis and b) the scientist has made an accurate assumption of the number of contributors.

The limitation of STRmix ™  is with four person mixtures.  This is great as previously it became difficult to deconvolute a 3 person mixture, and 4 person were virtually impossible.  So, we are a step ahead.  However, determining whether something is a four person mixture (or actually comprises DNA from more than four individuals) can be incredibly difficult.  Empirical analysis of mixed DNA profiles has shown that 99% of five person mixtures can be confused with four person or a three person mixtures and almost all six person mixtures resemble those of five, four or three person mixtures.    So, one scientist might say this is a four person mixture and use STRmix ™ to generate a likelihood ratio, whereas another scientist may say, I think this is a five person mixture and I am not able to conduct reliable statistical analyses.  And we end up in a similar position to the one we had prior to STRmix ™ same profile, different answers.

There’s a lengthy discussion to be had about the use of STRmix ™.  I certainly think there is a place for it, and have the utmost respect for the developers.  BUT, caution should be used.  We see frequent examples of data being omitted from the STRmix ™ deconvolution, as well as seeing discrepancies between the number of contributors declared by the government laboratory scientist versus what we believe is the more accurate number of contributors.  Whilst independent scientists are not able to re calculate the statistics, due to the prohibitive cost of the software package, we are able to review the input and output data and determine whether we believe the analysis is robust.

The issues are far more complex than I can ever explain in a short blog post, but I hope this gives you some insight into STRmix ™.  The advice would be, where there are questions arising from the DNA evidence, particularly where mixed DNA profiles have been obtained, instruct your own independent DNA expert whom has knowledge of the STRmix software.

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Whilst many of the topics covered were not new, even with cases such as Azaria Chamberlain, I was fascinated to learn new facts – such as the evidence that was admitted into court surrounding the ability of a dingo to open it’s mouth wide enough to fit a babies head.

Many of the legal presentations may have been a little too complex for me as a forensic scientist, but many were fascinating non the less.  But, the best part of this conference was the bringing together of the two fields, and encouraging us to engage with one another.  Something that we really don’t do enough of.

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Independent Forensic Services are pleased to announce that we have been invited to speak at the Legal Aid NSW Criminal Law Conference (July 1-3 2015).  Our presentation is titled ‘Avoiding miscarriages of justice – issues facing forensic biology/DNA evidence in 2015′.  In this presentation we will discuss recent technical and procedural changes relating to the handling of Forensic Biology and DNA evidence, and explain the resultant issues that give rise to the potential for miscarriages of justice to occur.  We hope to deliver an enlightening and engaging presentation, which aims to provoke some thought and discussion among the Criminal Law community.

Registrations can be made through Legal Aid NSW.   We look forward to seeing you there!

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• Legal Aid NSW Criminal Law Conference 2015, 1st – 3rd July 2015.  Cockle Bay Wharf, Sydney

Legal Aid NSW offer its lawyers, both in-house and in private practice, a comprehensive criminal law conference program that meets the needs of criminal law practitioners across a wide range of practice types. The program offers enough points to cover your annual MCLE needs, with at least one point in each of the core practice areas.   The program will be released towards the end of May 2015.

• 5th International Conference on Evidence Law and Forensic Science (ICELFS),  22 & 23 July 2015.  University of South Australia, Adelaide

This is a biennial research-intensive conference which brings together leaders in the fields of evidence law and forensic science from Asia, the USA, the UK, Continental Europe and Australia. The ICELFS programs support and promote interdisciplinary and international collaboration in law and forensic science. Delegates comprise judicial officers, practising and academic lawyers, forensic scientists, political scientists and postgraduate students in the relevant fields.

• 7th European Academy of Forensic Sciences (EAFS) Conference, 6-11 September 2015, Prague

The theme of this conference is ‘Pushing boundaries, working beyond borders’ and aims to bring together delegates from forensic science laboratories, academia, industry and trade and service companies.  Registrations are now open for this conference.

• 26th International Symposium on Human Identification (ISHI), 12th – 15th October 2015, Grapevine, Texas

For the past 25 years the International Symposium on Human Identification has been witness to new technologies, changing policies, and trends in forensics.  This conference has Kirk Bloodsworth (the first person to be exonerated from death row through post conviction DNA testing) as a keynote speaker, which is sure to be a unique and interesting presentation.  Registrations are now open for this conference.

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In November 2007 Meredith Kercher was found with her throat cut at the flat she shared with Amanda Knox (a US exchange student).  Three people were tried for her murder.  Amanda Knox and her Italian student boyfriend Raffaele Sollecito were convicted of murder and sexual violence in December 2009. Amanda Knox was sentenced to 26 years imprisonment and Raffaele Sollecito for 25.  Rudy Guede was also convicted and jailed for 30 years, later reduced to 16 years on appeal.

In October 2011, a jury freed Amanda Knox and Raffaele Sollecito on appeal, largely due to doubts that were raised about the forensic evidence against them.  However, in March 2013 prosecution launched an appeal to have a new trial ordered which was successful.  In January 2014 the guilty verdicts for Knox and Sollecito were reinstated by a court in Florence.  Then finally, in March 2015, Italy’s top appeals court overturned the convictions again and ended the long legal battle.

The convictions of Knox and Sollecito were based primarily upon DNA evidence.  DNA evidence, which in our opinion (and that of many other forensic scientists) was questionable.  DNA was obtained from a knife seized from the kitchen of Raffaele Sollecito.  A DNA profile matching Amanda Knox was obtained from the handle and a DNA profile matching Meredith Kercher detected on the blade.

The DNA profile matching Meredith Kercher obtained from the blade is very low level  – in fact, many of the peaks are below the standard reportable threshold used around the world.  This, in conjunction with the fact that no blood was detected on the blade is problematic as it means it is not possible to determine how the DNA was deposited.  The proposition presented by the prosecution team was that the knife was used to stab Meredith Kercher and then cleaned, leaving no trace of blood, but traces of DNA only.  In our opinion whilst we can’t exclude this possibility, it is an unlikely scenario. Could the findings be due to Meredith Kercher having contact with the knife at some point? Or could it be secondary transfer of the DNA via Sollecito or Knox (ie DNA from Meredith Kercher transferred through innocent contact to Sollecito or Knox is then transferred to the knife when preparing food).  In our opinion this is also possible.  Or finally, is it some form of contamination?  There has been significant criticism of the laboratory that processed the DNA samples, allegedly they were not an accredited laboratory, and they neglected to carry out many of the routine checks and procedures that a forensic DNA laboratory would invoke in order to monitor contamination.  The nature of the DNA profile is such that it is consistent with the types of DNA profiles resulting from contamination.

When evaluating the DNA profile obtained we would never have favoured that the DNA profile was the result of Meredith Kercher being stabbed.  However, the evidence was presented to the jury in that way and along with the presence of a DNA profile matching that of Amanda Knox on the handle,  it can be made to sound fairly convincing to a lay person (such as a jury member).

Just as troubling is a statement made by the judge in the original trial, stating ‘Knox handled the knife in a stabbing motion instead of a cutting one’. There is absolutely no scientific evidence or literature which supports any inference of that kind. This statement along with the DNA evidence pertaining to the knife would have undoubtedly played significant roles in pointing the jury towards a guilty verdict.

The DNA evidence wasn’t limited to the ‘double DNA’ knife as it became known in the media.  There was also a bra clasp originating from the underwear of Kercher.  This item was discovered at the crime scene over 40 days after the murder.  This fact in itself poses an issue – why had it been overlooked?  What had happened to that piece of evidence in that time?  It is known that the bra clasp had been moved within the crime scene at some time (as proven by video evidence).  The DNA profile obtained from the bra clasp was also very low level, but matched that of Raffaele Sollecito.  The same issue remains with this item, in that it is not possible to detect how the DNA was deposited.   Even more troubling was evidence from the crime scene videos of investigators not changing their gloves between handling items – thereby making it a real possibility that the traces of DNA could be investigator mediated.

Of course, we can only comment on the DNA evidence but the similarities seen between the DNA evidence in the Meredith Kercher case and many of the cases we encounter here in Australia are striking.  The scientist is not evaluating the findings – the court is being left to do it themselves.   We have never presented DNA evidence in this factual format – we feel our job is to present the findings in a meaningful way.  Why was the knife being tested?  The knife was being tested as it was a suspected murder weapon – therefore, we should address the question of whether there is any evidence to support that it was, or was not, the weapon.  Note our choice of words carefully – ‘is there any evidence to support’.  It’s true, we can’t definitively determine whether this knife was used as the murder weapon, but we can look at the results obtained and express an opinion, based wholly and substantially upon a combination of scientific literature, along with our training and expertise.   So, maybe the system won’t change in the near future, but the defence lawyers can seek to instruct their own expert (such as Independent Forensic Services) to provide an impartial and informed opinion on the evidence being presented by the prosecution.

Helen Roebuck & Jae Gerhard

The post DNA evidence in the murder of Meredith Kercher – how can we avoid similar miscarriages of justice in Australia? appeared first on Independent Forensic Services.

Cognitive forensics is now becoming a mainstream area of research, with increasing acknowledgement of the important role human factors play in forensic decision making. Thus far, the focus has been on contextual biasing, with substantial debate and disagreement between commentators and practitioners as to the role context information has in varying forensic processes.

However, the fields of cognitive forensics and psychology can provide a vast amount of additional relevant information to inform forensic disciplines. Importantly, contemporary psychological experimental approaches can be used to determine the ‘how and why’ elements of practitioners’ approach to casework, their decision making processes and even characterise behaviours that might lead to error.

Dr Ballantyne’s presentation will show how they used their research into biological examinations and DNA collection to demonstrate how observational and psychological studies can provide information about examiner behaviour, human factor predictors of examination success, and why context information is sometimes required for optimal performance.

The meeting is free for members of ANZFSS or $5 for non-members.  For further information, including the location, download the flyer here

The post ANZFSS NSW Branch Meeting – 18th March 2015 6pm appeared first on Independent Forensic Services.

The main factors giving rise to this concern are:

• the use of “Streamlined Forensic Reporting” – detailing facts of analyses but with no contextual interpretation as to what they might mean in individual cases;
• the growth of “fragmentation” of examinations – the practice of items being examined and tested by multiple organisations, resulting in scientists/crime scene officers working in isolation from each other and no one person having an overview of what all the results really mean.
• the police dictating precisely what forensic work should be undertaken and on items selected by them;

These changes result in the need for a more robust defence sector, with independent forensic experts that are not only qualified but who can ensure scientific results are scrutinised and challenged effectively so as to minimise, as far as possible, any potential for miscarriages of justice.

Unfortunately, as we all know, Legal Aid funding poses a challenge for the forensic science defence sector.  Furthermore, there are “experts” selling their services to the defence, with no authoritative check on their credentials.  As such, it is increasingly imperative that scientific evidence against your clients is scrutinised and challenged by experienced and competent scientists who can also present their findings and opinions robustly in Court. But how do you choose a provider from the range of individuals and organisations available?

Experience: look for depth and breadth of experience of the scientists – how many years have they been practising and across what forensic disciplines? Is the scientist experienced enough to pull together a holistic defence case from a fragmented prosecution case? Many providers only have experience in one narrow scientific area, such as DNA, but what about the other disciplines?

Court accepted: has the scientist demonstrable experience over many cases and been accepted as an expert witness in criminal courts? Do they have an established robust Court presence and style?

Quality: the global forensic science community has selected an international quality standard, ISO 17025. All prosecution providers accredited under ISO 17025to undertake work for the Police. Therefore, a defence provider should also work to this standard in order to be recognised as, at least, an “equal” in Court.

Legal Aid experience: Does the provider understand the Legal Aid system? It’s pointless having the “best” provider if their quotation is going to be rejected by the Legal Aid Agency.

So, how does Independent Forensic Services fulfil these requirements?

Directors Jae Gerhard and Helen Roebuck deliver quality services scrutinising and challenging forensic science evidence:

We have been active forensic scientists for over 12 years:  both working for government agencies here and in the UK since 2001, and having being actively involved in thousands of cases.  We have been specifically serving the defence since 2013, but work for both prosecution and defence as we are independent, as we believe Forensic Scientists should be.

Experienced across a range of disciplines: we are highly experienced Court-going expert witnesses, having presented evidence in DNA analysis & interpretation, blood pattern analysis, detection of body fluids and biological material, damage  and hair.

Holistic approach: with our breadth of experience, we can pull together results from across disciplines to give the defence a single, coherent and co-ordinated response to complex, but fragmented prosecution cases.

Working to ISO 17025: whilst we have not yet undergone accreditation, we are very experienced at setting up and working within accredited laboratories.  At IFS we adhere to the ISO 17025 guidelines, and work within our own quality management framework.

Working for Legal Aid and private clients: we are experienced in working on Legal Aid cases and understand the issues at hand.  We also offer a Legal Aid discounted rate as we appreciate funding can be limiting to the case.  However, we are not limited to Legal Aid cases.

Excellent customer service: we work as a duo to facilitate the provision of a quality service.  This includes rapid turn around times, excellent communication, and most importantly, we work with a peer review system – all opinions are checked and verified by a second scientist.

If you have a case involving forensic evidence against your client, talk to us about the services we can offer to look at the possibilities for a scientific challenge.

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Let’s start in the obvious place – what is the dictionary definition of the word expert: ‘a person who is very knowledgeable about or skillful in a particular area’.

So, one can be an expert in anything they like.  I would confidently say that my son is an expert in Thomas the Tank engine.  The difference between his expertise in Thomas and mine in Forensic Biology is that he doesn’t produce expert reports on the subject and attend court, in the same way that I do.  The reports I am required to produce contain complex technical information, that is read by persons with little or no scientific knowledge.  The in’s and out’s of Thomas the Tank engine on the other hand can be understood by pretty much anyone!

So, how does one become an expert?  In my case, I have been through the education system in the UK, and completed a University degree.  But, it is certainly a lot more than my degree that qualifies me as an expert in Forensic Biology.  What technically qualifies me as an expert is the significant training and mentoring that I have undergone within the industry; the competency testing; and the ongoing professional development.  But, remember, it is not me that determines whether I am an expert in my field – that is up to the court to decide.

In my view…anyone with a certain level of intelligence, and an aptitude for biology could learn the techniques and skills that I have learnt.  I believe it is how you apply those skills which can set an expert apart from their peers.  Standing up in court and simply stating fact, whilst is a requirement of an expert, should not be the only role of an expert witness.  What should stand us apart is our willingness to give an opinion on the factual evidence.  For example – I can tell you there is a blood stain.  I can tell you that there was a DNA profile obtained from that staining which matches the victim.  And, I can give you a very overwhelming and confusing statistic.  But is that the limit of my expertise?  And should it be?

I don’t believe so.  I believe my role is to aid the court (in particular the jury) in understanding what the factual evidence means.  So, there is blood, which might originate from the victim on the knife.  But is this significant in the context of the case?

Perhaps the easiest way for me to convey this is to present a case study:

A homicide occurred during which the deceased sustained multiple stab wounds.  A knife was recovered from the crime scene, and examined by a forensic biologist.  The report generated by the scientist listed the following results:

• Apparent blood staining was detected on the blade and a sample taken for DNA analysis – a DNA profile matching that of the victim was obtained
• The handle of the knife was swabbed in order to recover any DNA present – a DNA profile matching that of the suspect was obtained
• The only additional information that the report contained was a statistic relating to the DNA matches.

In my experience, if you gave that information to the average person, they would deduce that the evidence supports the view that the knife had been used by the suspect to injure the victim.

But was it?

On review of the case, the blood was in the form of a single drip on the blade.  This drop of blood, in conjunction with the DNA profile obtained was consistent with the victim being injured and bleeding within the vicinity of the knife, however there was no blood staining upon the knife to suggest that it had been used to injure him.   As such, the findings presented in the original report could have potentially misled the court.

 At Independent Forensic Services, we will always aim to provide an opinion on the findings in the context of the case.  So rather than just report DNA results – we will give an opinion on what these findings mean in the context of the case – and this is what we believe sets us apart.

We take pride in answering the questions that the jury don’t even know they should be asking.  In fact, we just do what I believe all Forensic Scientists should!

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