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 urine from a third survivor.
Authors of a previous paper in the Annals of Emergency Medicine surmised from the available evidence that the Moscow emergency services had not been informed of the use of the agent, but were instructed to bring opioid antagonists.