Detecting Hidden Stains: A New Light on Crime Scenes

The study explores how two different hyperspectral cameras can help forensic teams spot and identify bodily fluids on various surfaces. Researchers tested blood, semen, saliva, sweat, seven non‑bodily liquids, and mixed blood–semen stains. They placed these on nine types of surfaces that differed in colour and texture. One camera, operating from visible to near‑infrared light, was praised for its ease of use. The other camera captured shortwave‑infrared data, revealing specific chemical fingerprints that help confirm a stain’s identity. By combining the two sets of images, scientists could see and distinguish all tested fluids, no matter the background.The mixed blood–semen samples proved especially tricky. Using both cameras together made it easier to separate the two substances, showing how data fusion improves accuracy. The researchers applied a statistical method called orthogonal partial least squares‑discriminant analysis to process the complex information and confirm each stain type. Overall, the findings suggest that pairing visible‑near‑infrared imaging with shortwave‑infrared analysis boosts forensic detection. This approach could become a powerful tool for crime scene investigators, helping them uncover evidence that might otherwise be invisible.