In 2012, a team of researchers at the British chemical and biological defense laboratories at Porton Down found carfentanil and remifentanil in clothing from two British survivors of the 2002 Moscow theater hostage crisis and in the urine from a third survivor. The team concluded that the Russian military used an aerosol mist of carfentanil and remifentanil to subdue Chechen hostage takers.[6]