Is it possible that the so-called 'defence of provocation' may be increasingly undermined by advances in forensic pathology? How might this happen? Stan Waipouri's homicide case has prompted community interest in the scientific field of forensic pathology and its allied sciences. Fortunately, there is a new book out- Bill O'Brien's timely Invisible Evidence (2007) can provide new insights into this emerging field of police investigation. It isn't all as accelerated as it is in crime dramas like the CSI series, nor are technological advances usually able to match the requirements of fictional television drama time scales. Sometimes, the procedures described below may take months. What happens when police find a body at a crime scene? As I've noted in previous articles on forensic pathology, they promptly erect a closed-off crime scene investigation site so the pathologists can move to take samples. In the Waipouri case, this involved blood stains. These are transferred onto filter paper samplers and taken back to the police station, and thence onward to professional forensic labs, to be analysed, catalogued, and identified as particular exhibits in any forthcoming court case. Fibres from clothing can also be used to ascertain the presence of assailants at the crime scene as are sole impressions from footprints, matched with suspect footwear. During murder investigations, blood loss means that a bleeding body will leave particular splatter marks. If blood drips directly above a floor or other horizontal surface, it will leave circular marks. If blood drips from a wound at an angle, the blood spots are likely to be elongated, like an oval or an exclamation mark. Particular spot patterns can be traced back to particular attacks. If blood has splattered across the wall in a distinctive curtain-like pattern, then it is possible that the assailant used a baseball bat or other such weapon, which can be simulated through three dimensional computer simulations. Striated or serrated edges or irregularities on the surface of assault weapons or bullets may also leave impressions that can be used for identification purposes in relevant cases. If a major artery is cut during an assault or the act of homicide, then blood will spurt out at great speed, propelled by the pumping heart, and varying in intensity as the heart beat pulses. All of the above blood stains and patterns are transferred onto filter paper, which may then be treated with luminol, a chemical that produces particular fluorescent patterns in ultraviolet light, which can then be used to retrieve faint fingerprints, or other evidential traces present at the crime scene. DNA evidence is analysed for particular trace amino acid sequences, then placed in a capillary tube of fine calibre, and propelled through it, using an electrical charge. Particular amino acid sequences and fragments are then used to identify suspect DNA as either present at the crime scene, or not. The time of death can be established through inserting a temperature probe into the body, which loses 0.8 C per hour, except in the case of limbs, which cool faster. Blood will have pooled in the lowest area of the body to the ground, resulting in a pinkish colouration (lividity). Rigor mortis, bacterial internal consumption of the body, and other factors are also useful. Cause of death can also be established obvious bodily injury. Bruising, strangulation, deliberate electrocution or drowning all leave telltale burns and abrasions, as well as possible microscopic skin particles or hand, finger or sole print impressions on the body. Particular neck bone (hyoid) fractures occur in the context of strangulation that do not occur in hanging suicides. The above may be visible in terms of abrasions and cuts in the skin or lower dermal layers. From the above, questions arise. Should existing forensic facilities receive more government funding? Are we training enough forensic pathologists as a country, or are we losing graduates in this useful field of scientific endeavour through inadequate remuneration? Most significantly for us, given that hate crime legislation was enacted here and overseas because of the greater severity of aggravated assault associated with particular categories of victim, will the proliferation of forensic technologies enable victims of such aggravated assault to fair redress and properly punitive sentences for their assailants, instead of mitigated sentences due to the 'defence of provocation?" Only time will tell. Strongly Recommended - Bill O'Brien: Invisible Evidence: Forensics in New Zealand: Albany: David Bateman: 2007. Craig Young - 11th December 2007