Hair to Document Drug-Facilitated Crimes: Four Cases Involving Bromazepam

Abstract

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, so-called DFSA, robbery) has caused alarm in the general public. Drugs used can be difficult to detect (active products at low dosages, chemical instability), possess amnesic properties, and can be quickly cleared from body fluids. In case of long delay between the alleged crime and clinical examination, collection of blood or even urine can be of little value. This is the reason why this laboratory developed an original approach based on hair testing by liquid chromatography-tandem mass spectrometry. To explore the detectability of a single absorption of bromazepam in hair, two volunteers (male and female) received a 6-mg dose. A strand of hair was sampled about one month after exposure and was cut into three segments of 2-cm long. After pulverization, 20 mg of hair was incubated overnight in a phosphate buffer (pH 8.4). The aqueous phase was extracted with 5 mL of a mixture of diethyl ether/methylene chloride (80:20) in the presence of diazepam-d5, which was used as internal standard (IS). Hair extract was separated on a XTerra MS C18 column using a gradient of acetonitrile and formate buffer. Detection was based on two daughter ions: transitions m/z 316.0 to 182.2 and 209.3 and m/z 290.1 to 154.1 and 198.2 for bromazepam and the IS, respectively. In the hair of the two subjects, bromazepam was detected in the proximal segment at 0.8 and 4.7 pg/mg, respectively. Hair analysis was applied to four authentic criminal cases. In the two first cases, bromazepam tested positive in the corresponding hair segment at 5.7, and 10.3 pg/mg. In another case, head hair was sampled 19 weeks after the alleged offense, and its length (< 4 cm) did not allow analysis of the corresponding period. However, 4.1 pg/mg of bromazepam was quantified in the victim's pubic hair. In these three cases, concentrations were consistent with a single exposure to bromazepam. In the last case, bromazepam was detected at 15 pg/mg in the segment corresponding to the period of the alleged offence but also in the range 2 to 7 pg/mg in the four other consecutive segments, making a single exposure statement difficult.