| dc.description.abstract | The development and improvement of methods used for the estimation of the
postmortem interval (PMI) is a common area of research in forensic science. This
research was conducted to physically and chemically analyze pig carcass decomposition
on a soil surface using conventional and newly developed methods for the potential use in
estimating the PMI. Photographs of pig carcasses decomposing on forested and open
land were scored using a decomposition scoring system and decomposition scores were
related to accumulated degree days (ADD). Overall, the ADD values were significantly
different for the two groups of carcasses; however, the ADD values for the onset of each
score demonstrated more similarity between groups. Decomposition scoring results also
indicated that refinements must be made to the calculation of ADD to allow for a
meaningful comparison of pig and human decomposition. The decomposition of pig
carcasses altered the water content, pH and fatty acid content of soil. The fatty acids,
myristic, palmitic, palmitoleic, stearic and oleic acids were successfully extracted and
analyzed from decomposition soil. Palmitic, stearic and oleic acids were the most
abundant fatty acids detected whilst the levels of myristic and palmitoleic acids were
negligible in comparison. A three peak fatty acid cycle was also observed for each fatty
acid. Variations in soil pH and fatty acid content of decomposition soil have the potential
to indicate the presence of a decomposition site. Furthermore, a nonlinear diffusion
model was developed to predict the development of the cadaver decomposition island
(CDI) in soil over time. The simulation of the model indicated that the diffusion model
has the potential to generate PMI estimations for early stages of decomposition by
corresponding the effective radius of the CDI to a particular time point. The general
findings of this research indicate that more accurate methods for PMI estimations can
potentially be developed with further research. | en |
