Author Archives: vaiseyj

Can postmortem MRI be used to assess trajectories in gunshot victims?

International Journal of Legal Medicine 30 October 2015

Multi-detector computed tomography (MDCT) has proven to be of value for the reconstruction of trajectories of projectiles and the assessment of the injuries in deceased gunshot victim. For the depiction of soft tissue injury, MRI is superior to MDCT and MRI may be of value to assess trajectories. In a clinical setting, there are guidelines for the application of MRI in patients with projectiles or projectile fragments and with precautions MRI is safe for these patients. However, this has not been studied for the postmortem application of MRI from a forensic point of view.

Subjects and method
To assess the behaviour of projectiles, two ferromagnetic and one non-ferromagnetic projectile were exposed to the magnetic field of a 1.5- and 3-T MRI. Projectiles were placed in six phantoms with the characteristics of human muscle tissue, with and without a simulated trajectory in the gel. Before and after exposure to the magnetic field, the gelatine phantoms were imaged with MDCT to assess the position of the projectiles.

The ferromagnetic projectiles rotate to a position where their long axis is parallel to the z-axis of the magnetic field and five out of the six projectiles moved through, either through the simulated trajectory or through a new trajectory. This was observed in both the 1.5- and 3-T systems.

Ferromagnetic projectiles can rotate and migrate in a gelatine phantom. It is very likely that these projectiles will also migrate in a human body in a MRI system. Therefore, from a forensic point of view, postmortem MR will make a reconstruction of the trajectories in the body and of the reconstruction of the incident as a whole less reliable.

View the fulltext (QH staff only)

Relationship inference based on DNA mixtures

International Journal of Legal Medicine 05 November 2015

oday, there exists a number of tools for solving kinship cases. But what happens when information comes from a mixture? DNA mixtures are in general rarely seen in kinship cases, but in a case presented to the Norwegian Institute of Public Health, sample DNA was obtained after a rape case that resulted in an unwanted pregnancy and abortion. The only available DNA from the fetus came in form of a mixture with the mother, and it was of interest to find the father of the fetus. The mother (the victim), however, refused to give her reference data and so commonly used methods for paternity testing were no longer applicable. As this case illustrates, kinship cases involving mixtures and missing reference profiles do occur and make the use of existing methods rather inconvenient. We here present statistical methods that may handle general relationship inference based on DNA mixtures. The basic idea is that likelihood calculations for mixtures can be decomposed into a series of kinship problems. This formulation of the problem facilitates the use of kinship software. We present the freely available R package relMix which extends on the R version of Familias. Complicating factors like mutations, silent alleles, and θ-correction are then easily handled for quite general family relationships, and are included in the statistical methods we develop in this paper. The methods and their implementations are exemplified on the data from the rape case.

View the fulltext (QH staff only)

No jail time for driver who ran man over

Gold Coast Bulletin MEAGAN WEYMES November 06, 2015

A DESIGNATED driver who left a stranger with a fractured knee, arm and ribs after running him over has escaped time behind bars after being handed a suspended sentence.
Learner driver Joel Murtagh, 17, ran over Mark Shaw after a fight erupted between their drunk friends at a Gold Coast service station on Australia Day last year.
Shocking CCTV footage shows the incident unfold after one of Murtagh’s female friends appears to throw a bucket of water on Mr Shaw.
The move sparks a violent fight where two of Murtagh’s female friends appear to be assaulted by men in the other group.

Read full report:

Freshwater drowning in a child: A case study demonstrating the role of post-mortem computed tomography

Medicine, Science and the Law October 2015 vol. 55 no. 4 304-311

In recent years, modern imaging techniques have gained ground in forensics. A crucial question is whether virtual autopsy is capable of replacing traditional autopsy.
Forensic diagnosis of freshwater drowning (FWD) is based on the evidence of findings from external inspection (e.g. frothy fluid exuding from the mouth and nostrils), internal examination (e.g. pulmonary congestion, enlargement of heart chambers) and biochemical analysis (haemodilution), findings which are non-specific. The detection of diatoms in organs of the systemic circulation may be of some assistance, but this analysis is rarely performed and is of debatable validity.
An 18-month-old child was found dead at home in a swimming pool. Considering the family’s wishes to avoid autopsy, the district attorney authorised a whole-body post-mortem computed tomography scan (PMCT). The main imaging findings were frothy fluid in the upper airways, fluid in the trachea and main bronchi, many pulmonary nodular ground glass opacities (GGO) in non-dependent regions and haemodilution. CT imaging did not show any other forensically relevant abnormality.
A high concordance was found between the CT findings reported in the literature in cases of FWD and the imaging results. Thus, after the exclusion of other causes of death, advised by the forensic pathologist, the district attorney closed the case and the death was attributed to FWD.
This case report demonstrates that PMCT imaging in cases of suspected FWD can provide some important findings for the diagnosis of FWD as the cause of death.

Request a copy of the article (QH Staff only)

Development of a computational biomechanical infant model for the investigation of infant head injury by shaking

Medicine, Science and the Law October 2015 vol. 55 no. 4 291-299

The inertial loading thresholds for infant head injury are of profound medico-legal and safety-engineering significance. Injurious experimentation with infants is impossible, and physical and computational biomechanical modelling has been frustrated by a paucity of paediatric biomechanical data. This study describes the development of a computational infant model (MD Adams®) by combining radiological, kinematic, mechanical modelling and literature-based data. Previous studies have suggested the neck as critical in determining inertial head loading. The biomechanical effects of varying neck stiffness parameters during simulated shakes were investigated, measuring peak translational and rotational accelerations and rotational velocities at the vertex. A neck quasi-static stiffness of 0.6 Nm/deg and lowest rate-dependent stiffness predisposed the model infant head to the highest accelerations. Plotted against scaled infant injury tolerance curves, simulations produced head accelerations commensurate with those produced during simulated physical model shaking reported in the literature. The model provides a computational platform for the exploitation of improvements in head biofidelity for investigating a wider range of injurious scenarios.

Link to journal abstract:

Request a copy of the article (QH Staff only)

Gold Coast riverbank body: Police trying to identify teenage girl Greg Stolz November 6, 2015

POLICE are scouring missing persons databases after a body found on a Gold Coast riverbank was revealed to be a teenage girl.
A murder investigation had has been launched after three fishermen found the body late yesterday afternoon in the Pimpama River.
Regional crime co-ordinator Superintendent Dave Hutchinson said the body was badly decomposed, and he could only say it was that of a teenage girl with dark hair.

Read full news report:

Probability of detection of DNA deposited by habitual wearer and/or the second individual who touched the garment

Forensic Science International: Genetics Volume 20, January 2016

Available literature on the detection of transferred DNA does not address the interpretation issues in relation to who wore rather than touched the garment. To acquire a greater knowledge of the rate of detectable wearer, toucher and background DNA, 63 males wore their own underpants for 12 h. The inside-waistband was handled by one of 11 female volunteers for 15 s. The waist-band was mini-taped and subjected to DNA profiling with the AMPFℓSTR® NGM SElect™ kit.
The findings show that on worn garments the probability of observing reportable DNA profiles is 61.9%. The wearer was detected as a single profile or part of a mixed profile in 50.8% of samples. When the wearer was present in a mixture, he was always observed as the major contributor. The toucher was detected on 11.1% of underpants. Reportable background DNA (non-wearer and non-toucher) occurs in 14.3% of samples and may affect the assessment of who wore the garment.
Greater knowledge of the frequency of detection of reportable wearer DNA and/or toucher allows scientists to evaluate the likelihood of observing a matching profile if an individual wore a garment rather than touched it in disputed case scenarios.

Click here to read full text