A 16-year-old boy's death in San Francisco has been linked to cychlorphine, a synthetic opioid estimated to be ten times more potent than fentanyl, marking the drug's first confirmed fatality in the city. Dante Lacourte was found dead by his mother in their Nob Hill apartment in April, and the case has since led to four arrests and the seizure of more than 20,000 counterfeit pills, as authorities warn of a new and largely undetectable threat emerging after the fentanyl crisis.

Dante's mother discovered him unresponsive with blackened fluid coming from his nose and mouth, and attempts to revive him with two doses of Narcan failed. An autopsy later revealed cychlorphine in his system alongside two other unapproved synthetic drugs; the substance is undetectable by standard fentanyl test strips. Police traced his phone records to identify dealers, then made arrests in September in the Tenderloin and Bayview-Hunters Point neighbourhoods, recovering firearms, cash, and a range of narcotics including cocaine, MDMA and heroin. Officials, including San Francisco's mayor and district attorney, say they are working with the FDA to track the drug and prevent a repeat of the city being "caught flat-footed" as it was with fentanyl.