Several people in Nassau County have dropped dead from a powerful synthetic narcotic called fentanyl, according to the Nassau County Medical Examiner's Office.
Initially, authorities believed the victims overdosed on heroin, but further analysis showed they'd used fentanyl mixed with metamizole, a banned substance, that came in packets stamped with "24K" in red ink, police said.
Fentanyl is about 100 times more potent than morphine, according to police. In a medical setting, fentanyl is used to either treat severe pain or as an anesthetic.
Metamizole has been banned in the United States since 1977.
The Nassau County Medical Examiner's Office believes that the "24K" packets are being sold to drug users as heroin but in reality contain the deadly fentanyl and metamizole cocktail.