Drug-facilitated sexual assault and analytical toxicology: the role of LC-MS/MS

The use of a drug to modify a person's behavior for criminal gain is not a recent phenomenon. However, the recent increase in reports of drug-facilitated crimes (sexual assault, robbery) has caused alarm in the general public. Drugs involved can be pharmaceuticals, such as benzodiazepines (flunitrazepam, lorazepam, etc.), hypnotics (zopiclone, zolpidem), sedatives (neuroleptics, some histamine H1-antagonists) or anaesthetics (@c-hydroxybutyrate, ketamine), drugs of abuse, such as cannabis, ecstasy or lysergide, or more often ethanol. Drugs said to be used to facilitate sexual assaults can be difficult to detect (active products at low dosages, chemical instability), possess amnesic properties and can be rapidly cleared from the body (short half-life). We present here a case involving a 23-year old girl that declared a sexual assault 6 days after the event was said to have occurred. To the Police, the victim claimed a total amnesia of the offense associated with intense sedation. Toxicological analyses for unknown sedative drugs achieved by LC-MS/MS revealed the presence of zolpidem (Stilnox), a non-benzodiazepine hypnotic. Concentrations after 6 days were 16 and 32 pg/mL in blood and urine, respectively. The drug tested also positive in the corresponding hair segment at 0.75 pg/mg. The requested extraordinary sensitivity of LC-MS/MS appears as a pre-requisite to document any case involving drug-facilitated sexual assault.