Rohypnol, a treatment for insomnia, was legally available in more than sixty countries, and U.S.-bound travelers could bring a three-month supply into the country for their own personal use. On the street the drug acquired such monikers as roofies, rope, the forget pill, and roach. The drug is a sedative related to Valium but is ten times stronger than the latter. At $1 to $5 per pill, it was cheap and therefore popular with teenagers, who liked to combine it with alcohol. Demand for the pills inspired trafficking in the drug into the United States from Colombia and Mexico. Although it was confiscated by police in more than thirty states, its use appeared heaviest in Florida and Texas.

Local authorities soon had a new problem to face besides teenagers abusing the drug at rave parties. Like alcohol, roofies made some of its users fearless...