Abstract
Background: Blood marks analysis is a common technique used in forensics. However, current methods used have their limitations and deviations.
The most commonly used trigonometric model is based on the linear movement of a blood drop, which disregards air resistance and gravitational force which affects all mass points in an area of space. Objective: The aim of this paper is to map the flight trajectory of blood drops in an experimental environment with the use of a firearm and to evaluate the option of replacing the real world flight trajectory by a more accurately definable parabolic approximation.
Method: An experimental model was created which simulates the real world dispersion of blood in the case of firearm use. Blood samples with a volume of 100 ml were placed into a plastic bag and were shot at.
For the purpose of the experiment was prepared wooden chamber (dimensions: 2 x 2 x 2 m). Plastic bags containing blood samples were hanged in the chamber and positioned into the chamber's center.
Blood samples were shot at from a distance of two meters by a Taurus .357 magnum handgun. Magnum .357 FMJ ammunition was used.
Each shot was recorded by a high speed camera under a 90° angle placed on the sample's level in a 2 m distance from the chamber. Conclusions: The outcome of these comparisons shows that the real world flight trajectory differs very little from the ballistic curve and parabolic approximation under the given experimental conditions.
In crime reconstructions the angle of incidence (angle of impact) of a blood drop impacting a horizontal surface plays an important role. In this area the outcomes of the ballistic curve and the parabolic approximation are nearly