Theoretical and Experimental Investigation of Forward Spatter of Blood from a Gunshot

A theoretical model predicting forward blood spatter patterns resulting from a 9 mm Luger copper full metal jacket bullet gunshot wound is proposed. The chaotic disintegration of a blood layer located in the vicinity of the bullet is considered in the framework of percolation theory. The size distribution of the resulting blood droplets is determined which allows for the prediction of a blood spatter cloud being ejected from the rear side of the target where the bullet exits. Then, droplet trajectories are numerically predicted accounting for gravity and air drag which is affected by the experimentally verified collective aerodynamic interaction of droplets. The proposed model predicts the number and area of individual stains, as well as their distribution as a function of distance from the region of origin. The theoretical predictions are compared with experimental data acquired in this work fired from a 9 mm Glock model 19 and the agreement between the predicted and experimentally measured parameters is found to be good. Implications and future applications are discussed.