Sexual assault is a pervasive crime. The National Intimate Partner and Sexual Violence Survey estimates that 1 in 4 women will experience attempted or completed rape in her lifetime.[1]
Drug-facilitated sexual assault (DFSA) involves the use of so-called “date rape drugs,” such as GHB or alprazolam, to render the victim vulnerable to attack. It is vital to understand when a sexual assault involves the use of drugs, both to help determine consent and for sentencing purposes, as DFSA involves more severe sentences because the court considers it a more heinous crime.
The vast majority of sexual assaults are perpetrated by a person known to the victim.[2] If the victim has a foreign substance in their body, it can speak to their inability to consent and may substantiate whether a crime has occurred. However, delays in reporting sexual assault — which may be days, weeks, or even longer — can make it difficult to detect drugs in fluids such as blood and urine because the body eliminates these drugs within a short time (typically a few days, if not hours).
The National Institute of Justice (NIJ) has funded research to address the challenges of detecting DFSA for several years. This research includes projects that examine ways to improve forensic hair testing and how drugs modify blood proteins.
Hair Testing
One approach to the problem of delayed sexual assault reporting is to use hair as a sample because it can hold a “record” of drug exposure longer. Hair grows approximately one centimeter per month, so cutting a sample close to the root at least a month after the event can allow for drug testing within the corresponding timeframe.
Hair brings its own set of challenges, however, including the lack of standard optimized procedures for testing. Labs may use different preparation methods for testing, which makes it difficult to compare results from different labs for interpretation. Labs must consider many parameters when preparing hair for testing. For example, should the hair be cut finely or ground into a powder? How many washes are needed to wash the drugs out of the hair and into the solution for testing? What solvents should be used and in what order? How long should each wash be? Changing one parameter at a time could require dozens or even hundreds of experiments.
Anthony DeCaprio’s lab at Florida International University has employed a novel Design of Experiments method both to rapidly investigate these parameters and to understand the interactions among them. With NIJ funding in 2017[3] and 2018,[4] DeCaprio explored a method to successfully extract various drug classes from hair samples. Using a consistent methodology can allow for better comparison across studies that examine other aspects of drug hair testing, such as the effects of hair characteristics like color and texture. In 2023, NIJ provided DeCaprio with additional funding to further improve the performance and reliability of forensic hair testing.
Blood Proteins
With funding from NIJ, DeCaprio is also exploring methods to analyze blood samples more effectively. After a few days, a drug or its metabolite will no longer be present in blood. However, DeCaprio and his students are investigating how a drug can modify the blood’s proteins, such as hemoglobin.[5] A drug or its breakdown product can attach itself to these large proteins, and chemists can detect the new components with very sensitive instrumentation. This combination of protein and drug or breakdown product, known as “protein adducts,” will persist in the blood much longer than the original drug itself. This extends the potential testing window and provides a complementary or alternative approach to hair testing for DFSA.
Because the true scope of DFSA remains largely unknown, it is critical to better understand which drugs are used to commit sexual assaults and how often. NIJ remains committed to funding research and advancing the technology to support DFSA victims.
About the Article
This article was published as part of NIJ Journal issue 286.
This article discusses the following awards:
- “Optimization of Pretreatment Parameters in Hair Analysis for Drugs of Abuse and Understanding Protein-Drug Physicochemical Interactions,” award number 2017-IJ-CX-0005
- “Evaluating Analytical Parameters and Understanding Drug-Matrix Interactions in Forensic Hair Analysis,” award number 2018-75-CX-0037
- “Novel Blood Protein Modification Assay for Retrospective Detection of Drug Exposure,” award number 2015-NE-BX-K001
- “Novel Blood Protein Modification Assay for Retrospective Detection of Drug Exposure – Development and Validation,” award number 2017-MU-BX-0002