"Many of the drug-related deaths are believed to be due to extensive multiple-drug use. The heroin-specific metabolite monoacetylmorphine was detected in 38 per cent of the deaths, but other substances were found to be present as well in 40 per cent of heroin/morphine-related deaths. Methadone was detected in 16 per cent of the deaths, but it was the only detected substance in only 18 cases. Amphetamine and/or methamphetamine and/or cocaine were detected in 16 per cent of the deaths."
Norwegian Institute for Alcohol and Drug Research, "The Drug Situation in Norway 2012: annual report to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)," (Oslo, Norway: December 2012), p. 35.