Bloodstain pattern analysis is of tremendous value for the investigation of the evidence at the crime scene. Analyzing the bloodstain patterns provides an appropriate method for retracing the origin of blood droplets and also reconstruction of the crime scene. The patterns of the bloodstains on the floors and walls are determined by the impact conditions of blood drops such as droplet sizes, impact angles and velocities. The objective of this work is to study the bloodstain patterns on an inclined surface, in order to categorize the bloodstain shapes. The experiments have been carried out using a 38% glycerol solution at room temperature between 16° C∼21° C. The experiments have been done for three different droplet diameters, five different velocities and four different surface inclinations. The blood-mimicking fluid viscosity and density have been measured at the same temperature range with the experiments. The results have been investigated in terms of bloodstain shape and patterns and three different categories have been determined. In addition, a new mathematical formula has been derived based on the equivalent diameter of the bloodstains, which relates the bloodstain dimensions to the droplet Reynolds and Weber numbers. It has been shown that the proposed formula fits more accurately with the experimental results for high impact angle cases as compared to the classical formula.

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