Forensic scientists at West Virginia University have made groundbreaking discoveries in the field of gunshot residue (GSR) analysis. With the emergence of environmentally friendly ammunition, traditional methods of GSR analysis have become obsolete, necessitating innovative approaches. By understanding the behavior of GSR on different surfaces such as skin, hair, and fabric, crime scene investigators can make quicker and more informed decisions in forensic laboratories.
Traditionally, the presence of lead and other toxic components in ammunition helped establish the presence of GSR at crime scenes. However, the advent of “green” ammunition, which is devoid of heavy metals, has rendered these conventional methods ineffective. Tatiana Trejos, an associate professor at the Department of Forensic and Investigative Science, explains that when a gun is fired, a cloud of particles is released by the primer, containing inorganic compounds like lead, barium, and antimony. These particles come into contact with the skin and leave behind a unique combination of metals that indicate firearm discharge, aiding forensic investigations.
However, the shift towards eco-friendly ammunition has eliminated the presence of heavy metals in primers, posing a challenge for GSR analysis. In the absence of heavy metals, researchers must explore other compounds such as nitroglycerine, which are released during firing. By combining information about both organic and inorganic compounds in GSR, forensic scientists can increase the reliability of their results. Luis Arroyo, an analytical chemist and associate professor, highlights the importance of studying organic gunshot residue as it offers opportunities to confirm the presence of GSR that would otherwise be missed.
Trejos and Arroyo conducted extensive studies to investigate the persistence and transfer of organic and inorganic compounds of GSR on various surfaces and during different activities like running, handshaking, and washing. The research, published in a Forensic Chemistry paper, involved the development of new and improved reference standards for organic and inorganic GSR. These standards facilitated the accurate replication of real-world GSR, enabling meaningful comparisons between different laboratories.
The team applied these particles to fabrics, human skin, and an artificial skin product called Strat-M. They then subjected these surfaces to real and simulated activities before measuring the remaining particles. The experiments revealed that inorganic GSR particles tend to persist for longer periods on surfaces such as palms or sweatshirts, compared to organic compounds. However, they are more susceptible to loss or transfer through common activities. For example, washing hands with soap and water followed by drying with a paper towel can prevent the identification of inorganic GSR particles like lead, barium, and antimony on the hands.
In contrast, organic compounds may be lost from clothing if a suspect resists arrest, but they are less likely to transfer to others, such as the arresting officer, during activities like handshaking. Handshaking can result in the transfer of up to 100 inorganic particles from one person to another, while no transfer occurs for organic compounds. However, organic particles tend to dissipate over time due to factors like evaporation from the skin.
The researchers also discovered that Strat-M, an artificial skin, can serve as a viable substitute for human skin. This finding opens up new possibilities for testing conditions that would be unsafe or impractical to conduct on real human skin.
While these research findings are significant, they need to be applied in conjunction with a recently developed methodology that allows field Crime Scene Investigators (CSIs) to analyze possible GSR immediately at a crime scene. However, Tatiana Trejos emphasizes that real-life CSIs do not have all the answers portrayed on television. While determining the presence of GSR can be answered with reasonable certainty, establishing whether a person fired the gun remains a challenge. Nevertheless, these advancements in GSR analysis pave the way for addressing questions that are crucial to judges and juries.
By providing faster and more informative investigative tools, these advancements assist law enforcement in apprehending offenders with solid evidence while minimizing the risk of false incarcerations. Keeping up with the evolving nature of ammunition and GSR is crucial in ensuring the accuracy and effectiveness of forensic science in solving crimes.
The revolutionary breakthroughs achieved by forensic scientists at West Virginia University have revolutionized gunshot residue analysis. Traditional methods are insufficient in the face of eco-friendly ammunition, necessitating innovative approaches to GSR analysis. By understanding the behavior of GSR on different surfaces and combining information about organic and inorganic compounds, crime scene investigators can make better-informed decisions. These advancements not only help in solving crimes but also ensure that justice is served with solid evidence and reduced chances of wrongful convictions. The constant evolution and adaptation of forensic science are essential in maintaining its accuracy and effectiveness.
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