Storage life of whole porcine blood used for bloodstain pattern analysis
ABSTRACT Bloodstain pattern analysis (BPA) can be critical for criminal investigations, for example by providing information on the events that have occurred. Reconstruction and scientific experiments conducted to understand such bloodstain patterns are multifaceted. An important variable that needs to be controlled is the blood source. In the BPA community it would be useful to know if storage conditions affect the properties of blood and any associated bloodstains. Knowing this would assist in appropriate experimental design for research and reconstruction purposes. The aim of this study was to investigate the effects of storage time and intraspecific variation of blood from different pigs on selected hematological properties (packed cell volume and plasma protein concentration) drop diameter and drip stain size of whole porcine blood with a liquid anticoagulant. Drip stains were generated from four different pigs' blood samples, and documented with high speed video and digital photography. Significant changes in packed cell volume, drop diameter, drip stain size and spreading ratio during storage (25 days) were identified using multilevel linear models. While a time frame for storing blood was not established, the complexity of the degradation and ageing of the stored blood became apparent. It is recommended that studies which seek to compare drip stain characteristics using blood stored over several days should include steps to monitor changes in blood properties with time and employ the use of a standard control surface to determine changes in stain characteristics over the duration of the experiment.