CSI
Researchers introduce a brand-new method to detect gunshot residue at the crime scene
Crime scene investigation may soon become significantly more accurate and efficient
Universiteit van Amsterdam
image:
Photoluminescent lead detection in gunshot residue. (A) Shooting firearms produces gunshot residue that typically contains lead particulates. (B) Methyl ammonium bromide in the reagent reacts with lead in gunshot residue to form perovskite, which emits bright green light upon illumination with UV light. (C) Typically, the combustion plume and bullet wipe contaminate objects such as clothing, hands, and targets with gunshot residue, which is rapidly visualized with photoluminescent lead detection to assess suspect involvement and to assist crime scene reconstruction. Image provided by AMOLF.
view moreCredit: AMOLF
Crime scene investigation may soon become significantly more accurate and efficient thanks to a new method for detecting gunshot residues. Researchers from the groups of Wim Noorduin (AMOLF / University of Amsterdam) and Arian van Asten (University of Amsterdam) developed the technique that converts lead particles found in gunshot residue into a light-emitting semiconductor. The method, published last month in 'Forensic Science International', is faster, more sensitive, and easier to use than current alternatives. Forensic experts at the Amsterdam police force are already testing it in actual crime scene investigations.
Gunshot Residue Clues
The innovative light-emitting lead analysis method offers exciting opportunities for crime scene investigations. When a weapon is fired, it leaves gunshot residue containing lead traces on the surrounding environment, including clothing and skin. Bente van Kralingen, a forensic expert at the Amsterdam Police, explains: "Obtaining an indication of gunshot residue at the crime scene is a major advantage, helping us answer key questions about shooting incidents. For instance, determining whether the damage found could have been caused by a bullet and determining the relative position of a person who might have been involved in a shooting incident. We test for lead traces on possible bullet holes and a suspect’s or a victim’s clothing or hands."
Currently, police send all samples to the lab for analysis. However, the methods used there are often time-consuming, labor-intensive, and require expensive equipment. "We’re excited about the tests we’re conducting, and hopefully this will allow us to use the light-emitting method soon in actual court cases as evidence," says Bente.
Semiconductor Technology
The new analysis method builds on recent advances in perovskite research. Perovskites are a promising material used in applications ranging from solar cells to LEDs. A few years ago, the research group of Wim Noorduin developed an easy-to-use lead detection method based on perovskite technology. In this method a reagent converts lead containing surfaces into a perovskite semiconductor. Shining with a UV lamp will make the newly formed semiconductor emit a bright green glow visible to the naked eye—making even small traces of lead easily detectable.
In 2021, Wim Noorduin and Lukas Helmbrecht (formerly PhD student in the group) established a start-up company to develop this lead testing method into a practical lead detection kit: Lumetallix. Over the past years, many people worldwide have been investigating their surroundings using the Lumetallix test kit. They report positive tests in all sorts of objects, for example: dinner plates, beer glasses, but also in paint dust at construction sites.
Lukas Helmbrecht developed an altered version of the Lumetallix reagent for the forensic application: one that reacts especially well with lead atoms in gunshot residue and produces a long-lasting green glow.
At the shooting range
To validate the effectiveness of this method, the researchers conducted a series of controlled experiments. PhD students Kendra Adelberg and Arno van der Weijden (AMOLF/UvA) visited a shooting range in Amsterdam. Kendra: "We used standard 9 mm full metal jacket bullets and fired them from two different pistols at cotton cloth targets placed at various distances. After applying the reagent, we visualized the gunshot residue patterns. The results revealed well-defined luminescent patterns that were clearly visible to the naked eye, even at extended distances," says Kendra.
During their experiments, Kendra and her colleagues made two other remarkable discoveries. Firstly, unlike other methods, the new light-emitting technique remains effective even after extensive washing of the shooter’s hands. This is important for forensic investigations, as suspects often try to tamper with or remove evidence of their involvement. Secondly, bystanders standing approximately two meters away from the shooter also tested positive for lead traces on their hands. "These findings provide valuable pieces of the puzzle when reconstructing a shooting incident. But, a positive test also needs to be carefully interpreted, it does not automatically mean that you fired a gun." says Kendra.
Who Will Benefit?
The researchers believe this new method will be especially beneficial to first responders, such as police officers, who can use it to rapidly screen potential suspects and witnesses to secure crucial evidence.
Beyond forensic applications, the team is also exploring the potential of this light-emitting method to detect lead contamination in environmental samples such as water and soil. Since lead is toxic and harmful to the environment, this research could have broader implications for environmental monitoring and public health.
Reference
Kendra Adelberg, Arno van der Weijden, Lukas Helmbrecht, Diede Blaauw, Arian C. van Asten, Willem L. Noorduin, Perovskite-based photoluminescent detection of lead particles in gunshot residue, Forensic Science International, 370, 112415, March 9th (2025). https://doi.org/10.1016/j.forsciint.2025.112415
(A) Color marked areas for gunshot residue testing. (B) Direct lead testing on shooter’s hand showing bright green luminescence. (C) Lead testing on the hand of bystander after shooting showing moderate luminescence, and (D) weak luminescence after washing with water and soap. (E) Bystander’s hand after thorough washing still showing clear green luminescence on nails. (F) Indirect lead testing by wiping glass fiber cloth over clothing of a bystander shows bright luminescence. (G) Indirect testing of bystander’s shoe sole. (H) SEM stub after stubbing shooter’s hand showing green luminescence where lead is present. Image provided by AMOLF.
Credit
AMOLF
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Journal
Forensic Science International
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Perovskite-based photoluminescent detection of lead particles in gunshot residue
