The forensic investigation of any death is a vital and important process that involves different exporters to find the truth through scientific evidence. A particular investigation that we will be examining is the death of a pedestrian from a ‘hit and run’ accident. Although car accidents are not a major cause of death, they are quite a lot of cases and they are always very tragic. This investigation will investigate a deliberate ‘hit and run’ where the pedestrian experienced tertiary impact, causing many fatal injuries and then was run-over by the driver.
The first rule of any locus is to preserve it and therefore it quite strictly off bounds to anyone except those that are required to go and inspect the death. Therefore the first police officer(s) at the locus has the responsibility for initiating scene preservation procedures [Saferstein, 2001]. This includes setting up road closures, establishing cordons, initiating scene logs and in some cases noting environmental points as evidence can be compromised due to change of weather conditions.
They also, whenever possible, gathers information from witnesses, emergency personnel, and bystanders and try to get a description of what happened or anyone saw the individual or vehicle that was responsible. This information is important for different reasons. It helps to establish the outer perimeter of the scene, and it assists in determining the series of events that may have occurred.
Various other expertises all work at the locus as well such as the pathologist, the Prosecutor Fiscal, photographer, the toxicologist and the crime scene investigator, who is the main person that decides who gets to go into a scene and in some cases establishes an entry and exit path for the period of the scene examination [Saferstein, 2001]. Everything must be noted all the experts have a vital role of recording all the procedures that are done and documentation for every expert is required to be competed for future reference that could help the case.
The Prosecutor Fiscal is a local representative of the Lord Advocate and there responsibility is to investigate and prosecute crime, including all sudden unexpected deaths and natural deaths – In this case a car accident. The Prosecutor Fiscal then comes to a judgment whether the death is natural or perhaps suspicious. If the death is suspicious, as in our case then a full investigation is undertaken where a pathologist, toxicologist, forensic scientist and any other expertise will all be asked to contribute their skills in specific areas.
As for the role of the forensic scientist is twofold: to analyze physical evidence found on a victim on the scene of a crime and compare it to evidence found on a suspect and to provide expert testimony in a court An extensive search of the locus is carried out to find any evidence such as tire traces, broken glass and paint smears are searched for. When vehicles are painted more than one layer is painted onto the body’s surface – a primer, a filler, a coat, and then a topcoat – and if a car scratches on a certain object that paint can be deposited on that object.
Therefore paint smears left from the car smashing or scrapping against certain objects on the road, for example lamp post or barriers can be used to help determine some of the properties of the vehicle that caused the accident. The international forensic automotive paint data query database (PDQ) can then be used to determine the make and model of the vehicle based upon the paint trace’s chemical arid colour information [Royal Canadian Mounted Police (2005)]. Photographing the scene and all the physical evidence is conducted after the initial search has been conducted, the physical evidence is identified.
Different photography techniques such as painting with flash and oblique flash techniques are employed depending on the environment around [Blizter 2002)]. Time exposure photography and painting with flash are techniques that can be used at night scene examinations. Depending on available lighting conditions, painting with flash can provide extra lighting in darkened areas of the scene. The flash unit allows vehicles, debris, and tire tracks to be visible in long distance photographs, which would otherwise not be visible in normal flash photography.
Glass is primarily composed of silicon dioxide (Si02), which may vary from glass to glass.. The vehicles glass smashed when the deceased crashed into the front window allowing small fragments to fall on the road. These fragments can also be collect from the deceased’s clothes, hair, and head injury. Then the forensic scientist can compare them with a source window if later found to determine whether a link can be established [Curran et al. 2000]. Tire tracks can be treated as shoeprints and can be dealt with similarly.
The forensic scientist looks for tire marks in this case they would be latent and patent (2D) tire tracks. Information about the tire size is extracted from the trace, which helps to identify the make and model of the tire by using published references and electronic databases [Foster and Freeman (2005)]. It is also possible to find out which vehicles have such tires and to cross-reference those to the dimensions of the vehicle extracted from the tracks. If the vehicle is later found the tire marks may be used as an establishment of a link between the vehicle and locus.
The forensic pathologist is asked to come and attend the scene by the Prosecutor Fiscal and since the nature of the death is suspicious the autopsy later performed in the mortuary is a two doctor autopsy as the case is most likely to progress to criminal proceedings. The responsibility of the pathologists is to fully determine the cause of death through both and internal and external examination (post mortem), to determine circumstances around the death itself, give advice on the recovery of the body, to preserve evidence on the body and to identify who the deceased is.
The pathologists will try and establish a rough time of death by taking the temperature of the body via the rectal or by a Henssge Nomogram. A few other factors can be helpful to determine the time of death. Rigor mortis (stiffening of body) which occurs between just before 24 – 36 hours into death and by 48 hours disappears. The lividity (pooling of blood due to gravity) appears 1 – 2 hours after death and after 24 hours is fixed (Dr Rob Ainsworth, 18/01/11). This can also determine if the body was moved if the lividity was inaccurate with the way the body was discovered.
The two pathologists carry out the post mortem they start with an external examination which consists of recent or previous injuries; in this case there will be a huge number of injuries. The pathologist should look for facial impact injuries from when the deceased crashed their head into the front window screen and large scruff abrasions which can tell the direction the body fell. Also drag marks on the body where the driver ran over the deceased. General features such as height and weight, signs of disease.
Once the pathologists have carried out the external examination, photographs are then taken as evidence and for future referencing. Then the internal examination is carried out. One pathologist performs the post mortem and the other watches and takes down notes. Organs are removed, and each examining individually, samples are obtained and cause of death is searched for. In this case the pedestrian experienced a tertiary impact – body went into the air and then crashed head first onto the car and then on the ground.
The lungs are examined to see if there was any asphyxia from the impact of the fall and the head injury needs to be examined to see whether there was a subdural or extramural haemorrhage. One of these could be the cause of death. In order to examine what condition the deceased was in before the death a toxicologist must run through several tests on samples from the deceased. The toxicologist role is to analysis through various tests what toxins the deceased used if any, were they a long time drug abuser or not and was it the cause of death.
The pathologist gathers the samples for the toxicologist during the post mortem. Samples including femoral blood, urine, vitreous (substance that fills the centre of the eye), bile and any cavity fluid (bloating caused after death containing this liquid) are collected. The blood that gets analysed shows the recent ingestion and the recent drugs in the system of the deceased that they probably took before death. The urine is not always available but is higher is at a higher concentration therefore shows any previous use of drugs.
Hair can also show drug abuse as well as urine. In our scenario the pedestrian could be tested to see if he was under the influence on drugs, prescribed drugs or alcohol or if he was physically capable of looking after himself. As he could have a medical condition where he is not aware of what he is doing. After the post mortem and the toxicology test, the Prosecutor Fiscal comes to a decision as to whether there is a legal proceeding to be carried out in this case there could only be any legal proceeding of the driver that killed the deceased was identified and captured.
After the post mortem the Prosecutor Fiscal can release the body to the family for the appropriate disposal of the body after the death certificate is given. In conclusion, the investigation of a death of a pedestrian through a hit and run accident requires a variety of number of specialist, who co-ordinate together to come to the truth by the use of science and as science progresses methods of determining causes of deaths can be more quickly determined and defendants can be more accurately identified and brought to justice. This topic concerning car accidents is very disheartening and perhaps with the media high lightening car accidents, more drivers will become vary of the hazards of dangerous driving.
Blizter HL and Jacobia J. (2002) Forensic digital imaging and photography. Academic Press, London, England. Curran JM, Hicks TN, and Buckleton JS. (2000) Forensic interpretation of glass evidence, CRC Press, Boca Raton, FL. Dr Rob Ainsworth, 18/01/11 – lecture notes Foster and Freeman (2005) TreadMate – A reference database of vehicle tyres and tyre tread patterns to assist the identification of vehicles from crime scene data, available at http://www. osterfreeman. co. uk, last access performed on November 22, 2005. Foster and Freeman (2005) SICAR 6—Tyre mark and shoe print evidence management system, available at http://www. fosterfreeman. co. uk, last access performed on November 22, 2005. Royal Canadian Mounted Police (2005) RCMP fact sheets: Pain data query (PDQ), http:// www. rcmp. ca/factsheets/fact_pdq_e. htm, last access performed on November 22, 2005. Saferstein R. (2001) Criminalistics: An introduction to forensic science, T^ edition, Prentice Hall, Upper Saddle River, NJ.