The fatal overdose of a Traverse City man in December was caused by acute carfentanil intoxication, according to a new blood toxicology report from Western Michigan University School of Medicine. The findings prompted the Traverse City Police Department to issue a safety warning Wednesday cautioning the public about the highly potent compound.

Thirty-two-year-old Nathaniel Glen Clark was discovered dead in his car in the parking lot of Tom's on Fourteenth Street on December 4. An initial autopsy determined the cause of death was an apparent drug overdose. A blood toxicology report released Wednesday identified the specific cause of death as acute carfentanil intoxication. Carfentanil is a synthetic opioid used as a tranquilizing agent for elephants and other large mammals. According to the TCPD, "it is approximately 10,000 times more potent than morphine and 100 times more potent than fentanyl."

The department issued a warning urging the public to use "extreme caution when encountering any unknown substance suspected to be an illicit narcotic, especially those believed to contain fentanyl or a fentanyl-related compound." The substances can come in a variety of forms, including powders, blotting papers, tablets, patches and sprays. Carfentanil can also resemble powdered cocaine or heroin. According to the Drug Enforcement Agency, it is 40 to 50 times stronger than street-level heroin and can be fatal in doses as small as two milligrams. "A very small amount ingested, or absorbed through your skin, can kill you," according to the DEA.