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Abstract

Prior to 1955, bloodstain evidence was considered to be unreliable and therefore inadmissible in a court of law. Today, DNA profiles can be derived from leukocytes, which comprise less than 1% of our total blood volume. Aside from genetic profiles, the biological and physical properties of blood can reveal a great deal to investigators. The first landmark case to utilize blood’s class characteristics reliably was in the State of Ohio vs. Samuel Sheppard. This paper explains how viscosity, surface tension, flow, velocity, and Newtonian laws of motion can be used to determine: the relative locations of victims and offenders, handedness of an offender, and the weapon used. Discussion of these properties reveals not only that blood possesses evidentiary value, but that Dr. Samuel Shephard was not guilty of murdering his wife. It should be noted that although blood typing and DNA are other biological properties of blood that should be considered in casework, this paper focuses on how biological properties of bloodstain patterns can reveal details of what occurred at the scene of a crime, rather than its application in identifying the individuals who shed the blood.

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