Deep in the heart of the Adirondacks, the unexpected death of a small-town police sergeant has added fuel to a nationwide controversy over an herbal supplement.

On August 6, 2017, police cruisers raced down blacktopped country roads in Tupper Lake, New York, to Haymeadow Road, their sirens piercing the tranquil summer day. A medical emergency had been called in from just over the village line, and the address was immediately recognizable to anyone in local law enforcement: it was the home of an off-duty sergeant and his girlfriend. That day, nearly every officer in the Village of Tupper Lake police department, which employs 11, had been at the station putting together a search warrant. Soon, close to a dozen officers—village police, state troopers, and even an officer from the environmental-conservation police—swarmed the home and began working on their unresponsive 27-year-old colleague, sergeant Matthew Dana. Despite their efforts, no one could revive him and he was soon pronounced dead. They were all left wondering: What exactly had gone wrong?