wound photography

 

Photographing wounds (and controlling distortion)

  • use a lens with an appropriate focal length (70-120mm usually)
  • select an appropriate view point
  • ensure the scale (e.g. the American Board of Forensic Odontology (ABFO) scale) is not bent/ distorted
  • ensure the scale is in plane with subject (possibly fixed to something to hold it steady)
  • take a 'locator shot' i.e. a view including entire scale (check for distortion using circular markings on ABFO standard scale)
  • take additional 'close up' view(s) of subject
  • ensure that both axes of the scale are parallel to the film/ imaging plane (i.e. perpendicular to the long axis of the lens)
  • if injury is on a curved surface, take several views 'around' the injured skin surface, using the scale perpendicular to the long axis of the lens

 

 

angle distortion of arm abrasion ( © Marc Smith WIFM)

 

angle distortion of arm abrasion close up ( © Marc Smith WIFM)

 

no angle distortion of same arm abrasion ( © Marc Smith WIFM)

 

distortion from bending scale ( © Marc Smith WIFM)

 

 

See also:

  • Sheasby and MacDonald 2001 for a discussion of the effects of distortion on the evaluation of bitemarks
  • UV photography - Hempling 1981; Barsley et al 1990; Krauss 1985; West et al 1992
  • Red-free and infrared photography of bruises - Tetley 2005; Shore 2003

 

 

other wound imaging techniques

 

Superimposition

Several techniques have emerged in recent years in which researchers have attempted to analyse wounds and injuries in innovative ways, and to demonstrate pathological findings of injuries and wound patterns in court settings.

Forensic scientists and pathologists have utilised the use of superimposition for many years, such as when comparing skulls with the photographs of missing persons, matching ante-mortem with post-mortem features. The technique was famously utilised in the Buck Ruxton case in 1935.

The advent of video superimposition allowed jurors to visualise the correlation with ‘fading’ in and out of features of interest.

Patterned injuries can also be treated in a similar way with modern software packages. The wound or injury in question, as well as alleged weapons or implements must all be photographed with a scale, so that they can, in turn, be superimposed and a ‘best fit’ can be determined.

Photographs of injuries can be distasteful and harrowing for jurors to look at, and can be termed ‘prejudicial’ in some cases, and thus subject to a judicial ruling of ‘inadmissibility’. One way of removing this potential threat is in the use of body diagrams, or computer generated ‘body models’.

Such computer generated images can be used to ‘map out’ injuries based on measurements and descriptions of wounds made at the examination stage, and are more aesthetically ‘pleasing’ to the eye.

 

 

Generating 'body map illustrations'

With the advent of photo-realistic animation software (such as ‘Poser ®’) allows not only a realistic ‘model’ on which to illustrate wounds and injuries, but can also be taken a step further – the body model can be animated so that wounds can be viewed from different angles and perspectives.

 

March et al (2004) worked closely with forensic practitioners to animate the interaction between victim and assailant via the implement inflicting the wound(s).

Using software that allows the ‘stripping away of body layers’, the wound track of a knife, for example can be shown to correlate to certain body positions, and be shown to be incompatible with other body conformations.

Prosecution and defence scenarios can therefore be ‘played out’ and compared with anatomical data obtained during the examination of the wound/ body, allowing jurors to make up their own mind as to the likelihood of the various scenarios.

3D imaging, CAD and photogrammetry

Subke et al (2000 pp. 289-295) describe a method of recording the body surface in a 3D colour, photo realistic fashion – called Streifenlichttopometrie (SLT).

This technique records the body surface as 3D co-ordinates and records the natural colour of the skin, as well as that of any injuries present. These 3D co-ordinates can be manipulated to allow body segments to be examined in detail and data sets can be transferred into CAD systems in order to generate animated/ geometrical reconstructions.

Thali et al (2000 pp.281-287) further describe the use of Forensic CAD-supported Photogrammetry (FPHG) for documenting injuries and reconstructive analysis, where a series of photographs is taken of the injury at different angles. This series is scanned into the ‘Rolleimetric’ multi-slice evaluation system, and from there into a 3D-CAD program.

This technique is particularly effective when analysing patterned injuries, where a goal is to determine whether a particular implement caused that injury. It was noted in the late 19th Century that abrasions could indicate the shape of the causative agent and the manner in which it had been used in order to create the injury seen (Thali et al 2003 (a) p.177), but the use of 2D overlay techniques had considerable limitations. 

For example, the skin is elastic, and this gives rise to a disparity between the relative sizes of injury and implement causing it. The presence of bone underlying skin, the angle of impact and the movement of the body prior impact can all distort the wound, affecting the ability to match suspected implements to a photograph of the wound at a later date.

Details of patterned objects suspected of causing injury can be similarly processed, with the result that graphic models of both the injury and the suspected implement can be rotated and overlain to determine points of similarity or matches.

These 3D models interact in ‘virtual space’, and are considered superior to 2D overlay techniques. They are a non-destructive means of providing information as to the relative match of suspect implement and injury, without having to bring the two items in physical proximity, and without having to potentially change the nature of the evidence by doing so.

Indeed, with the use of new portable optical 3D digitising systems (such as the Advanced TOpometric Sensor (ATOS) system utilised by Thali (2003 (b) p.203-208) the data can be imported into stereo lithography hardware and a true-to-life model created for presentation at court etc.

 

Computed Tomography (CT)/ Magnetic Resonance Imaging (MRI) imaging techniques

Further advances in the use of novel imaging techniques include the use of Multi-slice CT and MRI for forensic autopsies. These modalities can offer the forensic pathologist clear images of wound and their sequelae, including gunshot wounds and the tracts made through soft tissues and bone.

Thali et al (2003 (c) pp.8-16) describe the use of their pioneering technique applied to the investigation of gunshot victims.

Researchers at the ‘Virtopsy’ (www.virtopsy.ch/) project have shown that CT/ MRI imaging can be extremely useful in forensic casework. In the UK, MRI scanners have been used for non-suspicious Coroner’s autopsies, and the evidence accepted by one Coroner.

The UK Government is said to be interested in the idea, but there are considerable obstacles to the widespread use of MRI autopsies – not least the lack of radiologists and scanners (the waiting list for a non-urgent MRI scan on the NHS is approximately 1 year). There is also a lack of solid evidence upon which to rely on an MRI autopsy in place of a traditional post-mortem examination (Wafer 2002 (a) pp.1-2; Wafer 2002 (b) p.6; Alderliesten et al 2003 pp.378-382; Bisset et al 2002 pp.1423-1424).

The Mac based Osirix software can be used to combine CT, MRI and other imaging data to provide 3D, 4D and 5D animations. (For example, see http://homepage.mac.com/rossetantoine/osirix/PICTS/HeadCT.mov for an example of 3D rendered imaging of the head combined with cross sectional data and 3D-Doctor imaging technique examples (http://www.ablesw.com/3d-doctor/images.html)).

 

Other techniques

 

 

 

examples of computer-aided or CT/ MRI visualisation of injuries

  • Bruises/ sub-cutaneous haematomas - Yen et al 2004
  • Patterned injuries
    • tyre marks - Thali et al 2000
    • baton - Oliver et al 1997
    • shoe imprints - Thali et al 2005
    • rubber bullet - Bruschweiler et al 2003
  • Abrasions - Thali et al 2003(b)
  • Knife wounds - March et al 2004
  • Gunshot wounds
    • gunshot wounds (general) - Thali et al 2003 (c)
    • muzzle imprint - Thali et al 2002; Thali et al 2003 (a)
    • shotgun entrance wound  - Thali et al 2003 (d)
    • rubber bullet patterned injury - Bruschweiler et al 2003
  • Bite marks - Thali et al 2003 (e)
  • 'Virtopsy' movie - 15 minute film providing an overview of the 'Virtopsy' project

 

 

references

 

 

 

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