David Foran in the lab
David Foran is the DNA expert that re-opened the Crippen case 100 years later, using DNA found on one of the original slides used in the trial to prove that the remains found in the basement were not those of Cora Crippen. Secrets of the Dead talked to David about his involvement in the Crippen investigation featured in “Executed in Error.”
SotD: How did you become involved in your role on re-examining the Crippen case?
Foran: I first became aware of the Crippen case when John Trestrail gave a talk at an American Academy of Forensic Sciences meeting several years ago. I have many years of experience working on these types of materials, including historical work of interest, such as our DNA analyses in the Boston Strangler case or the missing Lindbergh baby a few years ago. They are always fascinating.
When Beth Wills located maternal relatives of Cora Crippen, we were more than happy to test them. By the time we finished our DNA analysis on the Spilsbury slide, almost two years had passed, so it was not a quick undertaking.
Please briefly explain your lab’s role in providing the DNA analysis for Crippen’s criminal case.
The DNA analyses in the Crippen case was conducted in the Forensic Biology Laboratory at Michigan State University, which I direct. As is our norm for historical cases, this work was done pro bono.
The first samples we analyzed, in 2005, were from Cora Crippen’s grand-nieces and great-grand-niece, located by Beth Wills. All of these produced identical mitochondrial DNA sequences, which indicated (as expected) that the women were all maternally related.
The next challenge was obtaining samples from the burial in the Crippen house. An early request to the Scotland Yard Museum and The Royal London Hospital Archives and Museum (Barts and the London NHS Trust Archives and Museum) for the samples was pretty much rejected by both. So I contacted the same entities via email, letting them know what I and my lab could potentially do through DNA analyses with the hair and tissue (respectively) they had. Both groups had doubts, but after numerous back and forths, Scotland Yard said they would be willing to analyze a hair from the grave, for a fee. When I received the quote, the price was way over the top. So I continued working with Mr. Evans at the Archives and Museum, and he and his board agreed to send one of the Spilsbury slides to me as a museum loan. Knowing DNA work is destructive, it was an extremely nice gesture on their part. That slide made everything possible, and changed what had been assumed about the Crippen burial for the previous 100 years.
My lab’s mitochondrial DNA work, showing that the remains were not Cora, was released to the press by MSU in October of 2007, and it made a somewhat controversial splash in the U.K., as well as receiving a lot of interest from the U.S. to Norway to South Africa.
But, I and my lab had one more test we wanted to do—sexing the remains—using some new tools we have developed and perfected over the past few years. Those tests showed unequivocally that the remains were male (remember, all identifying features, including the sex organs, were missing). I decided to withhold that piece of information for the PBS film, so that they would have new material to include.
Is this the first time you’ve researched DNA this old? What are the challenges with samples like these?
I and my graduate students regularly work on biological material as old and much older than the Spilsbury slide. We have conducted a large amount of research on skeletal remains dating as far back as 1000 B.C. So the tissue on the slide was relatively fresh by our standards. And, since the tissue was housed in a museum, it was wonderfully preserved.
One tricky part was that the tissue on the slide had been treated with formaldehyde by Spilsbury, which preserves (‘fixes’) it, but makes DNA harder to recover and analyze. We have worked out specific techniques for obtaining DNA from tissues treated in this manner, so that problem was overcome.
Also, the adhesive Dr. Spilsbury used on the slide cover slip was a bit troublesome. He probably used pine resin (sap), given its yellowish color, and that made cover slip removal tricky. But once it was off, the ‘scar’ tissue was in fine condition.
From then on, it is the standard forensic DNA testing we regularly perform in the lab, with all the sundry controls and redundancy. As you might imagine, there was a lot more DNA work than what is portrayed in the film. I and my laboratory co-workers ran a battery of tests to prove to ourselves that the DNA came from the tissue on that slide, and nowhere else, for instance. Only when everything works exactly as it should, when we have repeated the testing and obtained the same results, and when we are as convinced and confident in them as is scientifically possible, do we release our results.
How long can a DNA sample be preserved?
DNA preservation is very dependent on where and how tissue or a sample is stored. In warm, wet conditions, tissue and DNA will degrade fairly quickly. Stored cool and/or dry, DNA can last a very long time. We have worked on skeletal remains just a few years old that are awful, and remains thousands of years old that are in quite good shape. And, the appearance doesn’t always predict DNA typing success. We have conducted research on the appearance (level of weathering) of bone and how that relates to DNA typing. Somewhat surprisingly, there is no correlation. So you cannot just look at a sample and know whether or not it harbors DNA.
For the Crippen work, a slide in a museum is a pretty nice way to preserve DNA. Compare that to bones that have been in the ground for thousands of years – you can guess which ones we would prefer.
How has forensic science progressed since Crippen’s time?
Obviously the techniques we have today far surpass anything that Dr. Spilsbury had available. Biologically, ABO blood typing was new then, and DNA hadn’t even been discovered. Dr. Spilsbury could not have performed tests similar to ours; it just wasn’t possible at the time. Today, remains such as those in the Crippen home would almost automatically be subjected to DNA testing. And in this case, the trial would have had a far different outcome.
In the same way, many individuals in the U.S. over the past few years have been exonerated of crimes they did not commit, based on new DNA evidence. People wrongly imprisoned for 10, 15, 20 years or more have been released, because DNA testing showed the prosecution, judge, and jury had the wrong person. It is very similar to the Crippen case, except now we can do something about it, at least sometimes.
I do need to remind everyone that the remains in the Crippen cellar were human, though we now know they were not Cora. Someone placed the remains there, maybe Dr. Crippen, maybe someone else. There is still a mystery out there.
What is the “next big thing” in DNA research?
I assume you don’t mean all DNA research, as that would include about a million different things.
The forensic sciences have really progressed over the past several years, both in the science itself, and in the professionalism with which that science is undertaken. Training and education are much better, as is oversight and quality control. That doesn’t mean there are not still problems, but today any problems are more and more likely to be caught.
DNA testing is now standard in the crime laboratories, but it continues to evolve. There is a push for processing samples faster and easier, which will lead to more robotics, automation, and miniaturization. Likewise, physical characteristics can be gleaned from DNA, such as hair and eye color. These can help reduce the pool of suspects.
Another new aspect of forensic DNA work is the sensitivity of testing. Not long ago a good blood stain or similar was required to get DNA results. Today we can sometimes obtain results from objects people have only handled (so-called “touch samples’”). In my laboratory we are conducting research on identifying individuals who assemble improvised explosive devices. IEDs have become well-known in Iraq, but they are also widely used in the U.S. We work with the Michigan State Police bomb squad, and after volunteers mock-assemble a device, it is armed and deflagrated. We collect the shrapnel and attempt to determine who assembled it based on remaining DNA. And you know what? We are getting pretty good at it.
