Rohypnol is the brand name for flunitrazepam, one of a widely used class of prescription medications known as benzodiazepines. Rohypnol is sold in 60 nations in Europe and Latin America by prescription, primarily as a sleep-inducing drug. It is also extremely debilitating, causing, in addition to deep sleep, amnesia and impaired judgment, especially when mixed with alcohol. It takes effect quickly, usually within 15 minutes of the time it is taken. When given secretly to a victim, she usually does not even know she has been given a drug. Victims of rapists who use the drug have no ability to fight off the attacker or to recall what happened. The drug, which is illegal in the United States, has created problems for prosecutors who attempt to prosecute rapes that have involved the use of the drug. A prosecutor in Broward County, Fla., where prosecutors have been obtaining convictions in Rohypnol rape cases, provides advice on what sort of evidence is useful in these cases. First, obtain as much information as quickly as possible while memories of potential witnesses are relatively fresh. Second, because the drug passes quickly through the system, obtain a urine sample from the victim within 24 hours of the rape if possible, so as to detect traces of the drug. Third, find out who may have seen the victim at the party, particularly anyone who saw and talked to the victim, saw who offered her a drink, noticed any changes in her behavior, or saw who escorted her from the party. Finally, look for people who heard someone brag about having used the drug.