Dutch investigators devise method to test for lubricant in sex crime investigations
Researchers at the Netherlands Forensic Institute (NFI) have developed a new chemical testing method to prove the presence of condom lubricant in sex crime investigations. This was previously impossible, which meant that if a rapist wore a condom and left no DNA evidence behind, there was often no physical evidence of the crime. “This evidence isn’t as strong as a DNA match. But it can certainly provide that extra push in an investigation, or refute a scenario,” NFI researcher Marc van Bochove said.
The Public Prosecution Service (OM) is delighted with this new method. “Sexual offenses are devastating for victims, but without witnesses, gathering evidence in sexual offenses is often complicated. At least two pieces of evidence are needed to reach a conviction. DNA traces are not always found when using a condom. This does not make the evidence any easier. Being able to demonstrate the presence of lubricant can help. A welcome development,” Wim ten Have of the Rotterdam OM said.
The new chemical analysis method allows investigators to detect much smaller quantities and map the chemical composition of the lubricant more accurately. This test will typically be used in rape investigations, but can also be useful in investigations where victims lost consciousness because their drink was spiked and woke up without knowing what happened. The presence of lubricant can prove that penetration with a condom occurred. The location where the lubricant was found can also tell investigators something of what happened.
The new method, liquid chromatography combined with high-resolution mass spectrometry, can detect strong indications of lubricant on samples taken from the victim approximately 48 hours after the crime, though the likelihood of this varies from case to case. “Even on samples initially used for DNA testing, we can now detect lubricant under certain circumstances,” Van Bochove said.
The NFI plans to conduct follow-up research to better understand the results of the research into lubricants in various offenses and circumstances.
