Crime Scene Investigation in CBRN Incidents

Chemical, Biological, Radiological, Nuclear and Explosives (CBRN-E) crimes represent an increasingly complex threat to public safety, national security, public health, and the environment. They expose crime scene investigators and first responders to significant hazards while often overlapping with environmental crime, hazardous waste trafficking, illicit use of dangerous substances, industrial incidents, and acts of terrorism. Although comprehensive global statistics remain limited, reports from international organisations indicate a growing number of incidents involving hazardous materials, highlighting the urgent need to strengthen national capabilities for investigating contaminated crime scenes. Crime scene investigation (CSI) plays a fundamental role in the criminal justice system by identifying, documenting, collecting, preserving, and analysing evidence that supports criminal investigations and subsequent prosecution. However, traditional forensic methodologies alone are insufficient when hazardous chemical, biological, radiological, or nuclear agents are present or suspected. Such environments require investigators to balance evidence preservation with responder safety, contamination control, decontamination procedures, and strict maintenance of the chain of custody to ensure the admissibility of evidence in criminal prosecution. This article presents a comprehensive framework for crime scene investigation under CBRN conditions, developed through comparative analysis of international guidance, operational experience, and lessons identified from real incidents, training activities, and multinational CBRN exercises. Drawing upon recommendations and best practices from the Organization for the Prohibition of Chemical Weapons (OPCW), the International Atomic Energy Agency (IAEA), the European Network of Forensic Science Institutes (ENFSI), and INTERPOL, the proposed framework integrates forensic science principles with CBRN emergency response requirements. The article explains the fundamental differences between conventional and CBRN crime scene investigations, describes the essential phases of the investigative process, and recommends enhanced procedures incorporating modern technologies and multidisciplinary cooperation. The proposed methodology aims to improve investigator safety, preserve forensic integrity, strengthen interagency coordination, and support the harmonisation of CBRN crime scene investigation practices across different jurisdictions.