In a unique solution that would make Doc Brown proud, a team of forensic scientists solved a 1988 rape case by going back to the beginning—leveraging the equipment and techniques that were considered the gold standard over three decades ago.
And if you’re going to resurrect a 30-year-old technology that has since gone by the wayside, what better place to do it than in the laboratory where it all started—the lab where Sir Alec Jeffreys first discovered the potential of DNA typing in forensic science.
It may sound like the plot of a good science fiction movie, but this is exactly how Catherine Turner and her team brought justice to a UK woman raped during a home invasion 33 years ago.
From old to new to old again
With a highly successful DNA database now in place, in 2014, the UK embarked on a large-scale project to review all unsolved sexual assaults from 1974 onward. Already providing dedicated DNA profiling services to police across the UK, Germany, France and Belgium, Eurofins Forensic Services was quick to get involved.
One of the cold cases involved the 1988 rape of a UK woman during a home invasion. Given the year, the DNA from the rape kit was originally tested using RFLP technology. At the time, it was compared to a few suspects, but there were no matches.
By 2014, the only evidence that remained was two microscope slides that had been prepared from the original swabs taken during the examination 26 years prior. Calling the slides “mini biological time capsules,” Catherine Turner, Scientific Adviser-Cold Cases for Eurofins Forensic Services, knew the team had to tread lightly if they had any chance of recovering cells and a DNA profile.
Working slowly with just one slide, the scientists were able to separate the sperm cells from other cell material, providing a sample strong enough to analyze with modern DNA profiling techniques. The testing revealed a low-level partial DNA profile that hit to an individual that lived only 200 yards form the victim at the time of the crime. This suspect also had relevant prior convictions and matched the victim’s physical description.
However, the team didn’t think that was enough for a successful prosecution. It was then Turner and her team asked a seemingly crazy question: since we still have the original results, can we go back and recreate the RFLP technique?
It was amazing to bring together the very first DNA technology with the very latest DNA technology.
Catherine Turner
As it turns out, the answer is yes—and what better place to do it than in the very laboratory where DNA typing was discovered? After many, many inquiries, Turner found help at the University of Leicester, who still had the lab and equipment used by Jeffreys when he was pioneering the use of DNA profiling for forensic applications in the 1980s.
According to Turner, it took her team over 2 years to painstakingly rebuild, test and validate the original RFLP process. They even had to spend time tracking down one of the original scientists from 30 years ago who used his own sample as an internal control on all the RFLP plates.
“We had to have a sample from him to ensure reproducibility of our own results,” Turner explained at her presentation during the 2021 Hit of the Year program at the HIDS conference today.
In 2017, after validation was finally complete, investigators arrested the suspect and took new reference samples.
“For this, we used three different types of DNA profiling—autosomal STRs, Y-STR profiling technique, and the resurrected RFLP technique. In each system, we had partial profiles, and they all matched the corresponding components in the suspect’s reference samples,” said Turner.
Ultimately, the suspect plead guilty and was sentenced to 10 years for rape and aggravated burglary.
“It was amazing to bring together the very first DNA technology with the very latest DNA technology,” Turner said.
Jeffreys agrees.
“What Catherine Turner and her colleagues did to resurrect the RFPL system was a huge challenge,” a now-retired Jeffreys told Forensic. “I commend them for their creatively, commitment and success with solving this case. I am pleased that the Hit of the Year program is recognizing this case. Highlighting cases like this reminds the world how DNA and forensic scientists are making our world a safer and just place.”
Photo: Sir Alec Jeffreys in his former lab at the University of Leicester. Credit: University of Leicester
Editor's Note: This is Forensic's second article on cases profiled during the 2021 Hit of the Year program at the HIDS Conference. You can read the first one here: How DNA Databases Solve Cold Case Rapes. The third and final article, about how a 48-hour case in Colorado is informing the next generation of DNA policy in the Philippines, will publish next week.