Duflou, Johan --- "Progress in forensic pathology and medico-legal investigations" [2020] PrecedentAULA 4; (2020) 156 Precedent 8

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PROGRESS IN FORENSIC PATHOLOGY AND MEDICO-LEGAL INVESTIGATIONS

By Professor Johan Duflou

Forensic pathology and its medical cousin, forensic medicine, are fields of medicine which probably interact with the law more than any other field of medicine. In most parts of the world, forensic medical practitioners practise a combination of medico-legal autopsy pathology and clinical forensic medicine. In contrast, the traditional Anglophone model is generally to treat these as two distinct fields of medicine, to a greater or lesser extent. While this model has allowed greater specialisation in the separate fields, it means that the potential offered by practitioners’ complementary skillsets and knowledge is perhaps not fully exploited.

In 2014, the Faculty of Clinical Forensic Medicine was established within the Royal College of Pathologists of Australasia (RCPA), placing clinical forensic medicine on a higher professional footing in the region with the aim of attaining formal recognition as a medical specialty. Joining the RCPA has allowed greater interaction between the two groups in Australasia, albeit that forensic pathologists largely work with the dead, while clinical forensic medical practitioners practise predominantly in the area of medico-legal practice involving the living. Given the critical shortages in forensic pathologists and forensic medical practitioners in many parts of the world, such developments can only be viewed as positive for the long-term health of these fields of medical practice.

Concurrently with these developments, there has been progress in multiple areas of forensic medical practice – including molecular biology and DNA technology, advanced imaging technology, toxicological insights, and a greater understanding of mechanisms of disease and injury – and with these advances a more robust scientific basis to the presentation of medical evidence. In this article, I examine a number of these developments as illustrations of progress in forensic medical practice.

THE MEDICO-LEGAL INVESTIGATION OF POTENTIAL FAMILIAL AND GENETIC DISEASES

DNA technology, where used for the purposes of identification in the form of DNA profiling, has revolutionised the identification and exclusion of suspects. DNA evidence is universally accepted as a powerful tool in the justice system, and advances in technology have allowed ever smaller and lower quality samples to be analysed. This remarkable progress has not been without a downside, with concerns raised in relation to the reliability of DNA databases, the ability of courts to understand the science, and the potential for contamination and laboratory error.^[1]

Less well known is the utility of DNA testing in the medico-legal setting for the identification of familial disease. The recent inquiry into the convictions of Kathleen Folbigg is an example where this emerging technology has been used in the justice system.^[2] Folbigg was convicted in 2003 on three counts of murder, one count of manslaughter and one count of maliciously inflicting grievous bodily harm in respect of the death of her four children between 1989 and 1999. Briefly, the four children, aged between 19 days and 18 months at the time of their deaths, had all died without evidence of significant traumatic injury, and although various pathological processes were identified in each child, it was the Crown case that all of the children had been deliberately suffocated by their mother. Although the issue of a potential familial or inherited cause for the four deaths was raised at the time of the two later autopsies, and at various times leading up to and after the trial in 2003, the state of DNA technology at the time was such that there was only limited investigation of possibly genetic causes. Advances in the field of genetics since the trial, together with stored specimens suitable for DNA testing in all four children and a specimen provided by Folbigg, allowed a reinvestigation of the possibility of a genetic cause of death in the siblings. Despite the prolonged time lapse between collection of the children’s samples and their testing in 2019, detailed DNA extraction, sequencing and analysis was possible to an extent which greatly exceeded the expectations of the experts involved in the inquiry, including Professor Kirk:

‘I think it’s remarkable that it was possible to perform testing of this type on these samples, and the resulting data quality was so good ... I don’t know that something like this has been attempted before, at least not in this kind of context, and the outcome was that we got very high quality data that was able to be interpreted.’^[3]

A total of almost 1,400 candidate genes were identified for analysis, including cardiac and non-cardiac genes associated with sudden death in infancy and childhood, genes associated with childhood neurological disorders, and genes associated with disorders in immunology and metabolism. Two teams of investigators, working independently with the data, made findings which were almost identical: namely, that no variants in genes were assessed as pathogenic or likely pathogenic in all four children so as to cause death. Both teams also identified a number of variants of uncertain significance, with the relevance of these genetic abnormalities being argued at length at the inquiry. Suffice to say that the inquiry concluded there was no reasonable possibility that any of the Folbigg children had a known or recognised genetic variant which caused their deaths.

The use of such genetic testing has had many successes as a major investigative tool for the investigation of sudden death and near-death events, especially in the young. Although quoted rates vary between jurisdictions, approximately 5 per cent of all autopsied deaths conclude with no cause of death identified. This is especially so in sudden death involving children and young adults, where the death remains unexplained following a routine autopsy in around 20 per cent of cases.^[4] In the explained natural death cases, about one third are the result of non-cardiac disease, such as asthma, epilepsy and a variety of other causes of sudden natural death, while the remainder are the result of structural heart disease, including premature coronary artery disease, various forms of cardiomyopathy, inflammation of the heart (or myocarditis) and various blood vessel defects, to list a selection of diverse pathology. Many of the negative autopsies, as well as many cardiac and to a lesser extent the non-cardiac causes of sudden death, have a strong genetic basis; further investigation of these cases using the ‘molecular autopsy’, or DNA testing for genetic disease, identifies a cause of death in a significant additional proportion of cases.^[5] This is, of course, not only highly significant from a coronial jurisdiction perspective but also provides answers to family members whose loved one has died. It further allows testing of surviving blood relatives for similar potentially lethal genetic abnormalities and their treatment.

POST-MORTEM IMAGING

Given that advanced imaging technology such as computed tomography (CT) scanning and magnetic resonance imaging (MRI) is a routine adjunct to medical diagnosis and treatment, forensic pathology and medico-legal death investigation have somewhat belatedly used these and other techniques as part of routine death investigation. Most capital city-based and some regional forensic pathology centres in Australasia now have either in-house CT scanners or convenient access to a hospital-based radiology service, and in many centres a CT scan is routinely done in the initial examination of the body. Based on those findings, a decision can then be made on whether it is necessary to progress to more invasive forms of examination.^[6] This has had the effect of decreasing the rate of coronial autopsies in most Australasian jurisdictions, and has also provided a novel way of presenting evidence of medical abnormalities and injuries before the courts given that explicit photographs may be considered too gruesome to present to the jury, and imaging technologies and 3D reconstructions can now be used to demonstrate bullet tracks and other injuries.

Despite these positive developments, problems with autopsy imaging persist. The cost of CT scanners is not trivial, and the cost of installing and running an MRI machine can involve many millions of dollars. Staffing is needed to run the equipment, and there is invariably a requirement for a significant upgrade in information technology resources. Further, forensic pathologists have traditionally received little training in interpretation of CT scan images, and radiologists who are prepared to enter this field even on a part-time basis are difficult to find and need additional training to interpret the various abnormalities which may be associated with the death process. Also, routine techniques used in the living, such as injection of contrast materials and other markers, present unique challenges in the case of a deceased person as a result of changes in their vasculature and a lack of circulation. Nevertheless, post-mortem imaging remains a growing area of medico-legal autopsy investigation, and although reports of the demise of the autopsy are likely somewhat premature, there is no doubt that imaging techniques can, in many cases, either augment or replace the autopsy investigation.^[7]

FORENSIC TOXICOLOGY

Intuitively, it would appear obvious that a blood level of a drug could be readily used to determine whether that drug has resulted in death or not. It is certainly the case that for some drugs this is not an unreasonable proposition. For example, a person found dead in a motor vehicle with the engine running, a suicide note and a blood carbon monoxide saturation of say 75 per cent can be reasonably assumed to have died of carbon monoxide poisoning (or more correctly of exhaust gas toxicity), and similarly a person with a blood cyanide level of say 100mg/L who was seen to ingest a quantity of potassium cyanide can be reasonably assumed to have died of cyanide poisoning. However, most drug intoxications are not so straightforward. For example, a person who has smoked methamphetamine or injected heroin can have a level of either drug of say 0.5mg/L. Such a level can be seen in a person who has had a fatal overdose of the drug, or who has taken the drug with a desired effect, or who is significantly intoxicated by the drug.^[8] Indeed, it is more often the case that the drug level, of itself, cannot be used to determine whether death was the result of overdose or not. For this reason, a detailed review of death circumstances and autopsy findings is required prior to making a confident determination of cause of death in the majority of cases. Added to this is the potential for interactions between consumed drugs to lead to a magnification of the toxic effects of each drug, and the fact that after death there can be significant alterations in drug levels in blood, in part as a result of processes such as post-mortem redistribution.

As opposed to most medical laboratory testing, where a request for the concentration of a specific substance, such as cholesterol, is sought, toxicological testing has the added problem of the nature of the offending drug usually not being known, adding to the complexity of these investigations. Further, novel psychoactive ‘party’ drug variants enter the consumer market on a near-daily basis, with associated difficulties in detecting, identifying and understanding the toxic effects and fatal levels of these drugs.^[9]

NECK COMPRESSION INJURIES

Both non-fatal and fatal compression of the neck is a significant public health and criminal justice problem. Non-fatal manual strangulation of an intimate partner has been shown to be a predictive factor for subsequent severe and/or homicidal violence against that partner, with a greater than seven-fold increased risk of subsequent homicide.^[10] This has been a driving force behind the introduction of specific offences relating to strangulation in multiple jurisdictions.^[11] The difficulty with many of these cases is one of identification and interpretation of the injuries. Therefore, although it is entirely possible for a person to have their neck manually compressed and for there to be no resultant injury, let alone injury which is characteristic of strangulation, many medico-legal reports conclude with the statement that the injuries observed (or lack of injuries as the case may be) are consistent with the provided history of an episode of manual strangulation. This, of course, can potentially mislead the court, and it is the exception rather than the rule that reports proffered by the prosecution indicate that the absence of injuries seen (or the presence of non-specific injuries) are consistent with the accused’s version of no neck compression.

So what does the research show? In cases of fatal manual strangulation, injuries to the surface of the neck are almost invariably seen, and other manifestations of asphyxia distant from the neck (such as facial or conjunctival petechial haemorrhages) are the norm, while injuries to the internal structures of the neck may or may not be seen.^[12] In non-fatal cases, as expected, such manifestations of injury are somewhat less common, with injury to the surface of the neck seen on around half of the complainants when examined by police,^[13] and some studies involving examination by trained forensic doctors finding external neck injuries in 85 to 94 per cent of cases.^[14] And some injuries which on initial cursory viewing may appear indicative of fingernail scratches and grab marks on the side of the neck typical of manual strangulation, may in fact have been caused during tugging and pulling on clothing and necklaces or similar during a struggle, and would of themselves not be a specific indication of neck compression.

Controversy in the area of neck compression is not limited to manual strangulation cases. Recently, there has been controversy surrounding the death in a New York jail of the American financier and convicted sex offender Jeffrey Epstein. At the time of writing, only limited detail is publicly available but what has been released is that corrections officers found the deceased hanging in his cell, and an autopsy reportedly identified three fractures of the larynx – one involving each of the superior cornus of the thyroid cartilage and one of the hyoid bone. Surprisingly, the data concerning fractures of the larynx in suicidal versus homicidal ligature neck compression is contradictory, with some studies documenting such fractures in around two-thirds of suicide cases, while other studies report such injuries as being exceptionally rare in suicides and much more common in homicides.^[15] As with all such cases, a detailed examination of the circumstances surrounding the death, together with a comprehensive autopsy which considers both the external appearances of the body and a meticulous dissection and examination of the neck structures and other parts of the body, will no doubt provide the definitive answer in the case. At least to those not wedded to conspiracy theories.

CONCLUDING REMARKS

This has been a short review of select areas of controversy and developments in forensic pathology and medico-legal investigations. It is certainly not intended to be comprehensive but more a means of illustrating some areas of interest to the author. As with all fields of scientific and medical endeavour, forensic medicine and pathology continue to evolve and new insights are identified. In common with the presentation of all expert evidence, medical and scientific opinions should be based on contemporary scientific thought and relevant research, which by their very nature are ever-changing and progressing bodies of work. With that come challenges associated with both legal and medical practitioners remaining up to date with those developments and controversies.

Professor Johan Duflou is a senior forensic pathologist practising from Sydney with extensive expertise in all aspects of forensic medicine and pathology, including injury assessment, mechanisms of injury, and their effects on the human body, both in living persons and in the deceased. As a specialist pathologist he also has in-depth knowledge of the mechanisms and effects of disease on the body. He has presented expert evidence in multiple jurisdictions in all states and territories in Australia and in many international jurisdictions. EMAIL [e-mail].

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¹ M Smith, M Mann, ‘Recent developments in DNA evidence’, Trends & issues in crime and criminal justice, No. 506, Canberra: Australian Institute of Criminology, 2015, <https://aic.gov.au/publications/tandi/tandi506>, accessed 3 November 2019.

^[2] State of New South Wales, Report of the Inquiry into the convictions of Kathleen Megan Folbigg (July 2019) <https://www.folbigginquiry.justice.nsw.gov.au/Documents/Report%20of%20the%20Inquiry%20into%20the%20convictions%20of%20Kathleen%20Megan%20Folbigg.pdf>, accessed 3 November 2019.

^[3] Ibid, 321.

^[4] R Bagnall, C Semsarian, ‘Role of the molecular autopsy in the investigation of sudden cardiac death’, Progress on Pediatric Cardiology, Vol. 45, 2017, 17–23.

^[5] R Bagnall, R Weintraub, J Ingles, J Duflou, et al, ‘Sudden cardiac death in the young: Results from a prospective population-based bi-national registry’, New England Journal of Medicine, Vol. 374, 2016, 2441–52.

^[6] See, eg, Coroners Act 2009 (NSW), s88; Coroners Act 2008 (Vic), s25; Coroners Act 2003 (Qld), s19; Coroners Act 1997 (ACT), s17A.

^[7] G Segal, ‘Coronial post-mortems: The demise of an antiquated process’, Precedent, No. 122, 2014, 38–42.

^[8] S Darke, S Kaye, J Duflou, ‘Rates, characteristics and circumstances of methamphetamine-related death: A national 7-year study’, Addiction, Vol. 112, 2017, 2191–201; S Darke, J Duflou, S Kaye, ‘Comparative toxicology of fatal heroin overdose cases and morphine positive homicide victims’, Addiction, Vol. 102, 2007, 1793–7.

^[9] S Darke, J Duflou, M Farrell, et al, Characteristics and circumstances of death related to new psychoactive substances. Drug and Alcohol Dependence (in press).

^[10] N Glass, K Laughon, J Campbell, et al, ‘Non-fatal strangulation is an important risk factor for homicide of women’, Journal of Emergency Medicine, Vol. 35, 2008, 329–35.

^[11] See, eg, Crimes Act 1900 (NSW), s37; Criminal Code 1899 (Qld), s315A.

^[12] V DiMaio, D DiMaio , Forensic Pathology, 2nd ed, CRC Press, Boca Raton, 2001.

^[13] G Strack, G McClane, D Hawley, ‘A review of 300 attempted strangulation cases. Part 1: Criminal legal issues’, Journal of Emergency Medicine, Vol. 21, 303–9.

^[14] L Shields, T Corey, B Weakley-Jones, D Stewart, ‘Living victims of strangulation: A 10 year review of cases in a metropolitan community’, American Journal of Forensic Medicine and Pathology, Vol. 31, 2010, 320–5; T Plattner, S Bollinger, U Zollinger, ‘Forensic assessment of survived strangulation’, Forensic Science International, Vol. 153, 2005, 202–7.

^[15] J Melinek, ‘Jeffrey Epstein: Hanging or strangulation?’, MedPage Today (online), 1 November 2019, <https://www.medpagetoday.com/blogs/working-stiff/83087>, accessed 3 November 2019.