The investigation of drug-facilitated sexual assault cases faces two major challenges. In addition to the race against time to detect substances that rapidly disappear from the body, investigators must also deal with the fact that a wide variety of different drugs can be used in these crimes.
To address these challenges, researchers from Prof. José Luiz da Costa’s group developed and validated a method capable of simultaneously detecting 57 drugs and metabolites in urine samples. Besides demonstrating high sensitivity, the protocol was successfully tested using samples collected from victims treated at the Toxicological Information and Assistance Center (CIATox) at the University of Campinas (Unicamp).
Far beyond the “Goodnight, Cinderella” crime
In Brazil, the expression “Goodnight, Cinderella” (“Boa Noite, Cinderela”) is commonly used to describe a type of crime in which the victim is drugged and subsequently robbed and/or sexually assaulted. Typically, the victim’s drink is adulterated with substances that induce drowsiness, disorientation, memory loss, or unconsciousness. Offenders exploit this state of vulnerability to commit theft, robbery, or sexual violence.
In these cases, the perpetrator secretly administers substances that are usually colorless and have little or no noticeable odor or taste. These drugs are often mixed with alcoholic beverages, helping to mask their initial effects. As a result, victims may believe they have simply had too much to drink, making it easier for the offender to “help” them by taking them elsewhere under the pretense of assisting their recovery.
The name “Goodnight, Cinderella” refers to the famous fairy tale, but its origin is often misunderstood. Because the crime involves drugging the victim, many people assume it should instead be called “Goodnight, Sleeping Beauty,” since Sleeping Beauty is the princess who famously falls into a long sleep.
In reality, the expression may have originated from a Brazilian television show hosted by Silvio Santos during the 1970s that bore the same name. Another possible explanation is that these crimes frequently occur at parties or nightclubs, evoking Cinderella’s iconic royal ball, where she famously loses her glass slipper. In the fairy tale, Cinderella also leaves before the end of the celebration, much like victims are often taken away before the event is over.
Drug-facilitated sexual assault
However, “Goodnight, Cinderella” represents only one part of a much broader problem. It is just one form of drug-facilitated sexual assault (DFSA). This type of violence does not occur solely when a drug is secretly added to a victim’s drink, as in the classic “Goodnight, Cinderella” scenario.
The term drug-facilitated sexual assault also encompasses a second situation. In many cases, the victim has voluntarily consumed alcohol or other drugs, but the perpetrator takes advantage of the victim’s impaired state to commit sexual assault.
Alcohol is the substance most frequently associated with these cases, although it is often combined with other drugs, such as anxiolytics (commonly known as tranquilizers) or even anesthetics. Despite their differences, these substances share a common feature: they depress the central nervous system, progressively reducing the victim’s ability to perceive and respond to what is happening.
Initially, they may produce a feeling of mild euphoria and reduced inhibitions, followed by impaired motor coordination, symptoms that closely resemble ordinary alcohol intoxication.
As time passes or larger amounts of the substance are consumed (for example, if additional doses are secretly added to the victim’s drink), the person may enter a deep sleep and eventually lose consciousness completely.
In many cases, victims also experience anterograde amnesia, meaning that once they regain consciousness, they are unable to remember what happened during the assault.
The combination of alcohol with other central nervous system depressants is particularly concerning. This interaction enhances the sedative effects of both substances, further impairing judgment, motor coordination, and the victim’s ability to react.
The challenge of finding evidence
Time is one of the greatest challenges in investigating drug-facilitated sexual assault. Many of the substances used in these crimes are rapidly absorbed and metabolized by the body, often within just a few hours. As a result, evidence of the assault quickly disappears from the victim’s bloodstream, making toxicological detection much more difficult.
Because these drugs frequently cause disorientation, drowsiness, and memory loss, many victims do not realize that an assault has occurred until much later. This delay in seeking medical care can further reduce the chances of obtaining toxicological evidence. In many cases, victims arrive at the hospital several hours (or even days) after the assault, when the drugs are no longer present in detectable concentrations in the blood.
Fortunately, there is a better biological sample than blood: urine. To understand why, it is important to know what happens to a drug once it enters the body. Before it can be eliminated, the body metabolizes it, breaking it down into smaller chemical compounds that are more easily excreted through urine.
These breakdown products are known as metabolites. They often remain detectable in urine for much longer than the parent drug remains detectable in blood. Consequently, toxicological evidence may be identified for one to five days after exposure, depending on the substance involved. For this reason, international guidelines recommend collecting urine samples as soon as possible whenever drug-facilitated sexual assault is suspected.
A new tool for forensic investigations
To improve the chances of finding toxicological evidence even several days after an assault, researchers from the University of Campinas (Unicamp), in collaboration with the São Paulo State Scientific Police and Thomas Jefferson University, developed a new analytical method specifically designed for drug-facilitated sexual assault investigations.
The study was published in the Journal of Analytical Toxicology. Its first author is Pharmacology PhD candidate Ma. Isadora Locilento Denkena, under the supervision of Prof. Dr. José Luiz da Costa, from the Analytical Toxicology Laboratory and the Toxicological Information and Assistance Center (CIATox) at Unicamp.
The goal of the study was to develop a single analytical test capable of simultaneously detecting a wide range of drugs commonly involved in drug-facilitated sexual assault, along with their metabolites. The method analyzes urine samples with sufficient sensitivity to detect extremely low concentrations of these compounds.
The protocol employs liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), one of the most advanced techniques available in analytical toxicology. We previously discussed this methodology in our article “New psychoactive substances (NPS): how can we monitor drugs that are constantly changing?“, which featured another research project led by Prof. José Luiz.
In simple terms, the instrument works in two stages. First, liquid chromatography separates the different compounds present in the urine, much like sorting thousands of mixed-up pieces of a jigsaw puzzle. Next, tandem mass spectrometry “weighs” each molecule and analyzes its chemical structure, allowing scientists to identify each compound with a high degree of accuracy.
The combination of liquid chromatography and tandem mass spectrometry (LC-MS/MS) makes it possible to detect extremely small amounts of a substance, on the order of nanograms per milliliter of urine. In addition, the technique can identify these compounds even among the thousands of other molecules naturally present in urine.
Beyond identifying the presence of these substances, the method is also quantitative, meaning that it measures the amount of each compound present in the urine. Knowing these concentrations provides valuable additional information for forensic investigations.
For example, the measured concentration may indicate whether the detected amount is consistent with intoxication or merely reflects therapeutic use. This distinction is particularly important because many of the substances involved in drug-facilitated sexual assault also have legitimate medical applications.
The protocol developed by the researchers can analyze 57 toxicologically relevant substances and their major metabolites, a substantial increase over previously developed methods in Brazil, such as a protocol created by researchers at the University of São Paulo (USP) that detects 16 substances. The panel includes prescription medications, illicit drugs, and other compounds commonly associated with cases of drug-facilitated sexual assault.
The selection of these substances was not arbitrary. Because Brazil still lacks a standardized national toxicological testing panel for drug-facilitated sexual assault cases, the researchers based their selection on recommendations from international organizations, including the Academy Standards Board (ANSI/ASB) and the United Nations Office on Drugs and Crime (UNODC).
The panel was further expanded to include drugs that are frequently encountered in the routine casework of the Analytical Toxicology Laboratory and CIATox at the University of Campinas (Unicamp), making the method better suited to the Brazilian forensic and clinical context.
From the laboratory bench to real-world cases
The first stage of the study involved validating the analytical method, ensuring that the newly developed protocol performed as intended. This validation step is essential to demonstrate that the results are accurate, reliable, and suitable for use in criminal investigations and forensic casework.
Once the method had been validated, the researchers evaluated its performance under real-world conditions. To do so, they analyzed 42 urine samples collected from individuals treated at CIATox following suspected cases of drug-facilitated sexual assault.
At least one drug or metabolite of toxicological interest was detected in 26 of the 42 samples (61.9%), demonstrating that the method is capable of identifying substances in actual forensic investigations. The detected compounds included alcohol, cocaine, cannabis metabolites, benzodiazepines, and other medications frequently associated with drug-facilitated sexual assault.
However, that detecting a substance alone does not prove that it was administered by the perpetrator. Some drugs may have been consumed voluntarily by the victim, prescribed as part of a medical treatment, or even administered during emergency medical care.
For this reason, toxicological findings must always be interpreted with caution and within the context of each individual case. Laboratory results should be considered alongside the victim’s account, medical history, the time elapsed between the assault and sample collection, and other evidence gathered during the investigation.
What did the analyses reveal?
Among the 42 urine samples analyzed, alcohol was the substance detected most frequently, being identified in 11 samples. Although public attention often focuses on so-called “date rape drugs,” alcohol remains the substance most commonly involved in drug-facilitated sexual assault, both because of its own depressant effects on the central nervous system and its ability to enhance the effects of other drugs.
Another frequently detected compound was THC-COOH (11-nor-9-carboxy-THC), the primary metabolite of tetrahydrocannabinol (THC), the main psychoactive component of cannabis. This metabolite was identified in seven samples and remains detectable in the body for a longer period than THC itself.
Cocaine and its metabolites were identified in five samples. The analyses also detected AEME (anhydroecgonine methyl ester, a compound produced when crack cocaine is smoked) as well as several benzodiazepines (a class of medications commonly prescribed to treat anxiety, insomnia, seizures, and other medical conditions). Antidepressants and antipsychotic drugs were also detected.
Benzodiazepines are of particular interest in forensic toxicology because they produce sedation, muscle relaxation, and, in some individuals, memory impairment. This effects are commonly associated with cases of “Goodnight, Cinderella” and other forms of drug-facilitated sexual assault.
Another important finding was that multiple substances were detected in the same urine sample in several cases. These combinations of drugs may produce additive or even synergistic pharmacological effects, further increasing impairment. This is one of the reasons why alcohol consumption is considered a major factor contributing to victim vulnerability in drug-facilitated sexual assault.
The study conducted by Prof. José Luiz da Costa’s research group and collaborators represents an important step forward in generating scientific evidence for a type of crime that remains poorly understood in Brazil. By expanding the range of substances investigated, increasing the sensitivity of toxicological analyses, and adapting international recommendations to the Brazilian context, the research provides a valuable contribution to forensic science.
The findings may also help improve our understanding of which drugs are most frequently involved in cases of drug-facilitated sexual assault, supporting the development of national protocols for victim care and toxicological investigations.
Ultimately, the new protocol strengthens the ability of forensic toxicology to support criminal investigations and provide more accurate answers for victims. In the investigation of these crimes, identifying a single molecule can provide crucial evidence for reconstructing events and helping the justice system establish the facts.
The research described in this article was supported by the São Paulo Research Foundation (FAPESP), grant No. 23/07323-1.
This article was also produced with the support of the São Paulo Research Foundation (FAPESP), Brazil, grant No. 25/17158-3. The opinions, hypotheses, conclusions, and recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of FAPESP.
Learn more
Research article describing the new analytical protocol (DOI: 10.1093/jat/bkag054)
Analytical Toxicology Laboratory at the University of Campinas (Unicamp)
The laboratory’s Instagram page
Toxicological Information and Assistance Center (CIATox) at Unicamp
The origin of the term “Goodnight, Cinderella”
Previous protocol developed at the University of São Paulo (USP)
United Nations Office on Drugs and Crime (UNODC)
Written by:
Mia Schezaro Ramos
Pharmacist. Ph.D. in Pharmacology. Science journalist, illustrator, trans, Nintendo enthusiast, K-pop fan, and dependent on physical exercise to stay sane.