Determination of the maximum distance blood spatter travels from a vertical impact

Bloodstain evidence can be very powerful evidence in assault related crimes. Determination of the distance that blood droplets may travel as a result of an impact into liquid blood may be of significance to corroborate or disprove a version of events, provide likely scenarios, or help determine the culpability of a person in determining their proximity to the blood shedding event. It was the aim of this research to determine the potential maximum distance blood droplets travel horizontally following a vertical impact into liquid blood. A custom apparatus was designed and constructed to replicate a vertical impact of a timber weapon, rotating on a fixed axis at one end, striking a pool of liquid blood. The device was positioned at three different levels of elevation to replicate an impact to the head of a person near ground level, a seated or kneeling height and standing height. Overall, the results indicated that the application of kinetic energy of between 1 and 5J at a height of 1780mm led to the blood droplets travelling a maximum horizontal distance of 5361mm (and average maximum distance of 4981mm). The horizontal distance blood droplets may travel upon impact does not appear to follow a linear trend with differing kinetic energy, but is affected by the applied force and release height in a curvilinear relationship. The results provide a valuable tool to bloodstain pattern analysts and investigators in determining search zones within a scene, as well as providing information about the proximity of an individual to an impact event.