Carlsbad, Oct. 21 -- Some of the people rushing to emergency rooms thought the CBD vape they inhaled would help like a gentle medicine. Others puffed it for fun.

What the vapors delivered instead was a jolt of synthetic marijuana, and with it an intense high of hallucinations and even seizures.

More than 50 people around Salt Lake City had been poisoned by the time the outbreak ended early last year, most by a vape called Yolo! - the acronym for "you only live once."

In recent months, hundreds of vape users have developed mysterious lung illnesses, and more than 30 have died. Yolo was different. Users knew immediately something was wrong.

Who was responsible for Yolo? Public health officials and criminal investigators couldn't figure ...