The Relationship Between Close-Range Shooting Distance and Nitrite Patterns on Cotton and Polyester Clothing

(1) The Neighborhood Academy, Pittsburgh, Pennsylvania

At a crime scene, the presence and pattern of gunshot residue can help forensic scientists piece together the events that occurred. To assist this, we determined the relationship between shooting distance and nitrite residue patterns left on fabric targets. Using the Modified Griess Test, we also investigated whether fabric type plays a role in gunshot residue (GSR) amounts. Cotton and polyester targets were shot from five different distances, and the targets were processed using the Modified Griess Test to measure the nitrite components of the GSR particles. An image processing program called ImageJ was used to approximate the total area of the residue. Results show that from 0 cm to 25 cm away, there was a rapid increase in GSR, but beyond 25 cm, there was a decrease in GSR, which is consistent with previous studies. Also, fabric type played a significant role in GSR patterns, with polyester fabrics holding more GSR on average than cotton at 25 cm, but less than cotton at 0 cm. The results of this study can potentially provide new and innovative ways to determine shooting distances and GSR patterns on different fabric types.

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