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From Weapon to Wall

其他書名	Investigating the Link Between Cast-off Bloodstain Patterns, Blood Dynamics and Assailant Kinematics
出版	University of Auckland, 2014
URL	http://books.google.com.hk/books?id=L9XloQEACAAJ&hl=&source=gbs_api

註釋Cast-off bloodstain patterns, resulting from blood being released from an object in motion, are frequently encountered at the scenes of violent assaults. The modern crime scene investigator may not be realising the full potential of a cast-off pattern in providing vital clues about crime dynamics. This dissertation examined three key components of cast-off pattern creation with the objective of developing a cast-off reconstructive framework: blood physical properties, the dynamics of small blood droplets relevant to cast-off patterns and the human kinematics used to swing weapons. In order to determine the uncertainty in blood droplet impact calculations from stains, an investigation into the variability of blood physical properties was undertaken and presented in Section 1. Significant variability was identified in the pig blood used for BPA in New Zealand. This variability was found to be due to biological variation and handling procedures so new methods of collection and handling were proposed in order to minimise adverse effects on blood sample quality. A method of normalising pig blood viscosity to within a small range helped to minimise the uncertainty in blood fluid dynamics results. Section 2 provided the first experimental investigation to study the relationship between stain morphology and the dynamics of small, upward-projected, fast-moving blood droplets. These results provided the experimentally-derived data on small blood droplet flight and impact dynamics which as significant implications for cast-off pattern analysis. The droplet-bloodstain relationships identified in Section 2 were tested in a 'real world' application; human-generated cast-off patterns were studied in a 3-D motion capture laboratory, presented in Section 3. The Section 3 experiments showed cast-off patterns to reflect the weapon trajectory, which was dictated by the human kinematics. Different kinematic strategies were used to swing different length weapons. The findings from these experiments supported the main hypothesis of the thesis, that cast-off patterns can be used to reconstruct the weapon trajectory which created the pattern. The experimental results from all three sections were combined to propose a cast-off reconstruction framework. This framework is designed to reconstruct dynamics movements at crime scenes, providing potentially invaluable information to a crime scene analyst.