The effects of environmental conditions on blood deterioration and blood detection in Tennessee

While blood is frequently present at the scene of a violent crime, little is known of its ability to survive in an outdoor environment. Most studies have been conducted in a laboratory, which is free of precipitation, severe temperature fluctuations and other environmental factors. It is the intent of this thesis to examine the cumulative effects of environmental conditions on blood deterioration and blood detection.

Three units of whole human blood were distributed on six different surfaces commonly found in an outdoor forensic situation. Three catalytic tests and one confirmatory test were used to determine the length of time blood was detectable on each surface. Gross physical changes in blood appearance were noted.

It was found that blood which is completely dry prior to the first rainfall is often long-lived even when only slightly protected from the elements. Differing lengths of time in which blood was detectable is attributed to surface texture, length and amount of rainfall, inclination of the surface and protection from the elements.