3-Methylfentanyl was also reported by Russian media as the identity of the anaesthetic "gas" Kolokol-1 (it may have been an aerosol, of a free base dissolved in halothane) used in the Moscow theater hostage crisis in 2002, in which many hostages died from accidental overdoses of the narcotic.
Although the exact nature of the active chemical has not been verified, the Russian language newspaper Gazeta claimed that the chemical used had been 3-methylfentanyl, attributing this information to "experts from the Moscow State University chemistry department."
It was first identified in the bodies of two drug overdose victims in Orange County, California, in December 1979, who appeared to have died from opiate overdose but tested negative for any known drugs of this type.