New research reveals the secret life left by bombs

Scientists have discovered key insights into how explosive materials are transferred to suspect hands, potentially changing the way evidence is evaluated in bombing investigations.

This pioneering study, published in the journal Science and Justice, examines how residues in smokeless powder (in pipe bombs and simple explosive devices) are transferred to the hands of the individuals who deal with them. Although forensic experts have long been able to find explosive residues in the hands of suspects, the interpretation of this evidence has been limited until now.

Dr Matteo Gallidabino, lecturer in forensic chemistry at King’s College London, and the study’s lead author highlights the importance of these findings. “These findings may mark a breakthrough for forensic investigations on individuals suspected of handling explosive materials,” he said. “Currently, forensic experts can identify the presence of molecules associated with explosive materials in their hands, but due to the lack of contextual data, the explanation is rarely deeper than that.”

“Currently, forensic experts can identify the presence of molecules associated with explosive materials in their hands, but due to the lack of contextual data, the explanation is rarely deeper than that.”

The research team conducted controlled experiments, and volunteers processed smokeless powder samples containing common additives after thorough washing of their hands. Participants rub the sample between their palms for 30 seconds, clapped their hands to remove loose particles, and then wiped their hands for analysis.

Perhaps the most surprising thing is that nothing matters: Contrary to expectations, the brand or type of smokeless powder seems to have little effect on the residual transfer pattern. Instead, two factors emerge as crucial factors – the amount of material of the processor and the unique characteristics.

These individual characteristics include physical characteristics such as skin characteristics and behavioral aspects such as processing techniques and application forces. Although not directly measured, these factors cause significant changes in residual metastasis.

The study is particularly relevant to investigations involving smokeless powders, which are still readily available to people who manually load their own gun ammunition. After the bombing, the suspect’s hand swab can detect these powder residues, but the assessment of someone’s actual handling of explosives is limited by inadequate data for background level, durability, and minor transfers.

The study found that the residual amount ranged from one billion to one million grams. Among the additives studied, dibenzylamine (DPA), dibutyl phthalate (DBP), and ethyl centripe (EC) (EC) always appeared at the highest concentrations, followed by DPA and EC. However, the different concentrations of these additives in different smoke-free powder brands are not reflected in the manual residues, thus enhancing the brand type is not a decisive factor.

As part of their work, the researchers also developed an optimized “filter and fire” technique, a simplified sample preparation method that could benefit future forensic research.

Dr. Gallidabino calls for further research to examine the wider range of explosive related substances and to study the retention and durability of traces over time.

“If we want forensic evidence to really help understand what is happening in a case, it is crucial to develop this understanding,” Dr. Gallidabino noted. “The results lay the foundations that can help experts better explain the residues in cases involving the use of energy materials, such as terrorist attacks, to draw stronger and more reliable conclusions in court.”