The presence of a drug in a drink raises suspicion about the nature of the case that needs forensic investigation. There can be different motives behind spiking beverages, which can range from miscarriage, abortion, and attempted murder through to sexual assault.The study of drugs in drinks and foodstuff can be an important aspect in forensic cases (HMA-v-Webster, 2012; R-v-Wilson, 2012).1 Generally drugs do not naturally occur in food and beverages with the exception of gamma-hydroxybutyric acid (GHB) which occurs in juices and wines produced by fermentation of grapes, particularly the red ones. The presence of a drug in a drink raises suspicion about the nature of the case that needs forensic investigation. There can be different motives behind spiking beverages, which can range from miscarriage, abortion, and attempted murder through to sexual assault.

Drug-facilitated sexual assault (DFSA) refers to a sexual activity without the consent or with the invalid consent when the victim is under the influence of drugs, noxious substances, or chemical agents. In recent years DFSA has been classified as “pro-active” (covert administration of a substance to the victim with the purpose of sexual assault) and “opportunistic” (where the victim has been rendered nearly or fully unconscious by their own actions prior to the sexual assault).2 DFSA differs from other sexual assault because the offender takes away the victim’s cognition and consciousness by drugging them without their knowledge and then sexually assaulting them. This is because of the effects of the drugs that victims unknowingly ingest which include sedation, impaired motor skills, and reduced level of consciousness and anterograde amnesia. Therefore, the victim is covertly drugged and severely debilitated by another person. In most circumstances this is someone who is known and trusted by the victim. Such incidents have generally happened when the victim is in a social or business situation that seemed non-threatening e.g. at a party, in a restaurant or club, at a friend’s house, or on a date. The victim consumes a drink as usual, however, within a short time the victim becomes unaware of what is happening and loses consciousness for a period of time. When consciousness is regained after a few hours, they have a little or no memory of the intervening time. Sometimes the victims find themselves naked or partially clothed and they may be physically distressed. This makes the situation more difficult for the victim to report to the police as he/she does not feel comfortable without knowing what happened. By the time the victim reports the case, generally a long period of time has elapsed and hence testing of the victim’s blood and urine are of no use because the drug will have been cleared. In such cases hair provides an ideal matrix for determining previous consumption of drugs since traces of any drug ingested are incorporated into hair as it grows. Infrequently considered in such cases are the drinks themselves through which the drug is alleged to have been administered. Consequently the analysis of suspected drinks (in cases where they are collected) and knowledge of the chemical decomposition of a drug in a drink becomes important.

DFSA is one of the most prevalent crimes in the UK. The Forensic Science Service (FSS) in the UK had to deal with about 500 claimed DFSA cases annually.3 Available data on DFSA indicate an increase in the number of such claims: 39 cases in 1990 and 935 cases in 2002 in Britain;3 and 30 cases in 1999 and 51 cases in 2005 reported for Northern Ireland alone.4 This increase may be related to better media coverage leading to an improved awareness, or the advent of drugs which are easier to administer without the victim’s knowledge.

Drugs of abuse are utilized in drug facilitated sexual assault due to their effects of sedation and amnesia in victims. The most prevalent drug to be identified in testing of samples provided in cases of alleged DFSA is ethanol.3 Benzodiazepines have also been found to be present in a significant number of suspected DFSA cases. It should also be noted that some of these detections may be due to prescribed or voluntary ingestion. Scott-Ham and Burton (2005) reported benzodiazepines in 9% of 1014 studied cases. Other drugs detected in alleged DFSA cases include cannabis, cocaine, GHB, LSD (lysergic acid diethylamine), opiates, barbiturates, and ketamine.

Despite the media popularity of flunitrazepam, a so called “date rape drug,” only a few cases have been reported worldwide. In response to the association of flunitrazepam with DFSA, Roche Products Limited, the manufacturer of Rohypnol (with flunitrazepam as an active ingredient), has reformulated the drug by making dissolution more difficult and formulating such that the solution changes to a bright blue color. However, other drugs containing flunitrazepam as their active substance are still available on the market. Most notable ones include Flunipam (1 mg flunitrazepam, Alpharma Inc, Norway) and Hypnodorm (1 mg flunitrazepam, Alphapharm Pty Ltd, Australia).

It is a common practice in forensic toxicology for blood and/or urine samples to be collected. The United Nations Office on Drugs and Crime (UNODC)2 guidelines for the forensic analysis of DFSA states the need for blood collection when the case is reported up to 48 hours after the alleged incident. Similarly, urine samples should be collected if the case is reported within five days of the alleged incident. However, in reality the majority of the drugs may have been eliminated from the system well before the five day limit. Therefore, recent researches have focused on the application of non-routine specimens such as hair. Head hair must be collected four weeks after the alleged incident in case of late reporting and also when the chronic exposure to drug must be assessed. The cups, drinking glasses, bottles, containers, and liquids left at the scene of alleged assault should be collected and submitted for analysis. They may provide useful information clarifying the events relating to alleged sexual assault if the drug residues are detected. Empty glasses, bottles, and vomit have all been submitted to the Forensic Science Service for analysis in cases of alleged DFSA.3 Various analytical techniques have been used to detect drugs from spiked beverages. These include chromatography and mass spectrometry based techniques, electrophoretic techniques, and chip based microfluidic systems.  

In an effort to contribute to developing a consolidated methodology for forensic investigation of DFSA cases, our research at Anglia Ruskin University has focused on laboratory analysis of the spiked beverages. Due to the frequency of detection of diazepam and temazepam in cases of DFSA in the UK and high media presence of flunitrazepam, our research group has focused upon the detection and stability of flunitrazepam, temazepam, and diazepam into a variety of beverages that were selected to represent common drinks consumed by women in the age ranges of 16–24, including an alcopop, a spirit, a white wine, a normal strength beer, and a fruit based non-alcoholic drink. Each study took place over a 25 day period. All three benzodiazepines were detected in the beverages at each time interval and storage condition studied, up to 25 days. This suggests that there is a need for change in practice at potential crime scenes and in investigation of DFSA. Drinks thought to be involved in DFSA cases should be routinely collected and analyzed where other evidence types do not assist in the investigation since, certainly in the case of benzodiazepines, the drugs persist for far longer in drinks than they do in the blood and urine of the victim. However, there are issues around the stability of flunitrazepam and temazepam,5 which show some decomposition in the 25 day time frame. It is therefore essential that samples should be analyzed as soon as possible after seizure.


  1. BBC News,;, Accessed on 5th April 2013.
  2. UNODC, Guidelines for the Forensic analysis of drugs facilitating sexual assault and other criminal acts, accessed 5th April 2013.
  3. Scott-Ham M., Burton F. C. Toxicological findings in cases of alleged drug facilitated sexual assault in the United Kingdom over a 3-year period, Journal of Clinical Forensic Medicine 12,175-186, 2005.
  4. Hall, J., Goodall, E. A., Moore, T. Alleged drug facilitated sexual assault (DFSA) in Northern Ireland from 1999 to 2005. A study of blood alcohol levels, Journal of Forensic and Legal Medicine 15, 497-504, 2008.
  5. Gautam, L., and Sharratt, S. Gas Chromatography- Mass Spectrometry Analysis of Benzodiazepines in Spiked Drinks under Different Storage Conditions. The Association of Forensic Toxicologists Conference, ,San Francisco, US, 2011.

Lata Gautam holds a B.Sc. (Hons.) and M.Sc. from Tribhuvan university in Nepal and a Ph.D. in Forensic Science from Anglia Ruskin University in the U.K. She is currently a Senior Lecturer in Forensic Science at Anglia Ruskin University. Her research interests include Forensic Toxicology and the analysis of drugs from biological matrices.

Mike Cole holds a B.A. (Hons.) in Natural Sciences from the University of Cambridge, U.K. and a Ph.D. in Natural Product Chemistry from the university of London. He is currently Professor of Forensic Science and Faculty Director of Research, Knowledge Transfer, and Scholarship in the Faculty of Science and Technology at Anglia Ruskin University. His research interests include development of analytical methods for street drugs and methods for drug comparison.