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Effects of Different Haematocrit Values on Estimation of Time since Deposition of Human Blood Stains Using Diffuse Reflectance Spectroscopy

Wellington, Emily (2017) Effects of Different Haematocrit Values on Estimation of Time since Deposition of Human Blood Stains Using Diffuse Reflectance Spectroscopy. Masters by Coursework thesis, Murdoch University.

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Abstract

Blood stains are a relatively common occurrence at scenes of violent crime and are a source of much information including biological, circumstantial, positional and potentially, information on the timeline of the crime. Successfully aging blood on scene could aid in time of death estimation, time since incident or even verify alibies of potential suspects. Methods in use thus far for time since death currently hold high error rates due to fluctuations in environmental factors. Several different techniques for aging of blood stains have been analysed and compared for suitability as well as similar spectroscopic techniques. Some of these aging methods were found to be complimentary, as reflectance spectroscopy has a relatively low error rate for short term aging, followed by a gradual increase, making it unsuitable for long term aging. Whereas, RNA marker analysis which follows the general degradation pattern of select RNA, was able to show a more steady error rate making it a more viable method for long term aging but not well suited to short term. The major variable factors in determining the time since deposition of blood stains include; daily or person to person fluctuations in blood protein percentages, haematocrit values, drugs present and environmental considerations such as temperature, humidity and UV light exposure. In order for any method to be acceptable in court, the full extent to these factors needs determination and full error analysis implemented. Additionally, improvement in portability, efficiency and development of non-destructive methods should be prioritised.

Publication Type: Thesis (Masters by Coursework)
Murdoch Affiliation: School of Veterinary and Life Sciences
Supervisor: Speers, James
URI: http://researchrepository.murdoch.edu.au/id/eprint/37794
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