system rapidly in just several days. >> it may be at the point the drug is not detectable. >> according to a 2008 review article from michigan state university, for every 100 rape cases reported only one-third are lead to prosecutors and only seven end with a prison sentence. >> former new york sex crimes prosecutor said if drugs aren't detected, prosecuting is very difficult. >> they're often not able to get up to recover in time to get themselves to a medical facility for the proper exam to see if drugs are still in the system. >> that's not the only challenge the drugs can cause amnesia. many times the victim can't remember what happened. the police need to build the case without the memory of the star witness. >> they have to find the bartender. i only gave her one beer. we're trying to take it out of the voluntary intoxication.