The US and UK have expressed growing concern that chemical weapons may have been used in Syria, most likely by government forces. Ralf Trapp, an international disarmament consultant who specialises in chemical and biological weapons, looks at how such evidence is collected and evaluated.
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Investigations of the alleged use of chemical weapons involve a variety of techniques to collect and analyse different types of evidence.
This includes interviews with survivors of the alleged attack and other eyewitnesses, such as first-responders and medical staff who treated the victims.
Inspectors would want to undertake medical examinations of the victims, and take biomedical samples such as urine or blood, which can be analysed for characteristic biomarkers and traces of the agent or its degradation products (metabolites) even if the incident has taken place some time ago.
Inspectors would also want to acquire samples from dead people or dead animals.
