Drug-facilitated crimes: Do not forget to test for GHB in hair!

Abstract

The aim of this paper is to promote the determination of GHB in hair to better document drug-facilitated crimes. Over the past years, there has been a dramatic increase in media reports about drug-facilitated crimes (DFC) victims. These reports evoked systematically the presence of GHB, but forensic toxicologists perfectly know that real cases are rare, at least in France. As exogenous GHB is rapidly eliminated (t1/2 approx. 30–60 min) there is a need of sampling victim's blood and urine very precociously: unfortunately, that is most of the time not possible due to delayed police report. Hair analysis remains the only solution to investigate these cases. We present here two DFC cases where GHB determination in hair gave the proof of GHB administration. Two different offenders used the same modus operandi at two different times, purporting as taxi drivers, that facilitated the reception of the victims and offering to drink a bottle of water. Victims (2 men) became confused and slightly asleep then loss motor skills; they awaked at home the morning after, suffering an anterograde amnesia. They found that their watches and their money had been stolen. Hair samples of the victims were collected 3 and 4.5 months after the offense. A targeted screening for drugs usually used in DFC cases was performed by LC-MS/MS. Hair were then tested for GHB. For each, a total of 8 small 0.5-cm segments from either side of the section of interest (i.e. the segment corresponding to the offense) were analyzed according to a standardized procedure: GHB-D6 (i.s.) was added to 10 mg hair from each segment before a 2-hours sonication in water; extraction was performed with ethyl acetate under acidic conditions; BSTFA derivatization was performed after evaporation of the organic layer. Chromatographic conditions were the following on a GC-MS/MS Trace 1300/TSQ 8000 (ThermoFisher): injection volume 2 μL; column 5% phenyl-95% dimethylpolysiloxane; temperature: 80 °C to 310 °C @ 15 °C/min. Analyzes for the common DFC drugs remained negative in both cases. Results for GHB are summarized as follow: case#1 GHB baseline was 2 ng/mg, GHB segments around the offense were 5.8 and 7.7 ng/mg. Case#2 GHB baseline was 1.3 ng/mg, GHB segments around the offense were 6.4 and 7.2 ng/mg. In both case the 2 segments near the root were excluded to avoid misinterpretation due to sweat contamination. The results were significantly different between the baselines and the offense-segments to conclude to a criminal administration of GHB or GBL. Moreover, the description of the clinical symptoms and memory loss were very typical of GHB ingestion. Our positive results were sufficient arguments to help the judge to charge 4 different fake taxi drivers with theft by trickery and with administration of poison, and to continue the investigation in seizing different household products presumed to contain GHB/GBL. It is important to notice that the fake taxi driver is a new way for robbery that appeared in recent years, operating in front of nightclubs, waiting most of the time for women but also for men who wanted to go home. Among all the drugs used to commit DFC (including DFSA), GHB is one of the most difficult to deal with in term of interpretation of the results. Hair testing for GHB is currently not an analytical problem (neither in blood and urine), thus it is a valuable reason to encourage testing for GHB in a sufficient number (8) of small hair segments (0.5 cm) to document DFC cases.