Science and Murder
In 1984, Dr. Alec Jeffreys, a British molecular biologist, had used Restriction Fragment Length Polymorphism (RFLP) as the DNA-typing protocol to dissolve an immigration dispute over a boy from Ghana who claimed he had a British mother and wanted to live with her. Dr. Jeffreys also resolved another paternity case, proving that a French adolescent was the father of a British-born child. He was able to assist in these cases because of his groundbreaking work in the lab at the University of Leicester. There he had looked for the small percentage of human DNA that shows individual variation, because that would provide a marker for definitive identification. Blood testing, even with all the protein profiles that could be identified, was still fairly fuzzy in this regard.
“I’d been working in Amsterdam with Dick Flavell,” Jeffreys said in an interview with
The Human Genome
. “We’d got to the point where we could detect single copies of human genes. But when I came to Leicester in 1977, I wanted to move away from the study of split genes, and to marry new techniques of molecular biology with human genetics.” He looked at the structure of genes to understand inherited variations among individuals, isolating a single nucleotide polymorphism (SNP) of DNA in 1978, then started to look for areas of DNA that would be more variable. This drew him to tandem repeat DNA, where a short sequence of DNA was repeated many times in a row. It seemed that these sequences would be open to duplication and recombination.
His task proved difficult at first, but Jeffreys’s work on the myoglobin gene, which produces the oxygen-carrying protein in muscle, yielded results. First he examined seal genes and then human, and there he identified a “minisatellite”—tandem repeat DNA. Jeffreys’s team used this to identify more minisatellites, through which they discovered a core sequence—part of DNA that remained constant throughout. They made a radioactive probe that contained the core sequences, which latched onto the diverse minisatellites simultaneously. Then they placed the results from different people on a blot. This was in September 1984, and when the blot was ready, Jeffreys and his colleague Vicky Wilson developed an X-ray of it. To their surprise, they discovered patterns, similar in appearance to grocery-store bar codes, that distinguished each subject from the others.
“There was a level of individual specificity,” said Dr. Jeffreys, “that was light years beyond anything that had been seen before.” He called this a “Eureka!” moment, and so it was. “Standing in front of these pictures in the darkroom, my life took a complete turn.” He set to work to refine the process and make it more manageable for identifying idiotypes, or patterns specific to all individuals except identical twins. He knew it could soon be used as a human identification system, what he called a genetic fingerprint.
For this work, Jeffreys and his colleagues received many public honors and in a paper published in
Nature
in 1985 (written with Drs. Peter Gill and David Werrett), they stated that an individual’s identifiable DNA pattern was unique and would not be found in any past, present, or future person. This put the doctor in demand for more paternity cases, a natural for this type of analysis. Yet he had a greater vision. Two years after the Lynda Mann murder, Dr. Jeffreys had stated to a Leicester newspaper reporter that “the new technique could mean a breakthrough in many areas, including the identification of criminals from a small sample of blood at the scene of the crime.” It was likely that officers on the task force had read the resulting article at the time of its publication, but it was the second incident that mobilized them to act on the information it contained.
Jeffreys had read newspaper stories about both victims, so he eagerly agreed to test the semen samples the police had obtained. They were packaged and sent to his lab, along with a blood sample from the suspect. Jeffreys had never tried genetic fingerprinting in a criminal case, but everyone on the police force felt certain that R.B.’s semen would prove their case, as well as confirm the technique’s viability. Since the sample from the Mann murder was fairly degraded, Jeffreys was uncertain about what to expect, but he put it through the lengthy RFLP process anyway and awaited the results.
In RFLP testing at this time, the extracted DNA was cut into fragments, then the fragments were covered in a gel to separate them into single strands. An electrical current was applied to push the negatively charged fragments through the gel at speeds relative to their length toward the positive pole, with the shorter pieces migrating faster. There they lined up according to size. The pieces were removed from the gel with a nylon membrane, called a Southern Blot, and the DNA fragments were fixed to the membrane. This process exposed the A, T, C, and G protein bases, which could then be treated with a radioactive genetic probe. The single-strand probe would bind to its complementary base, revealing the DNA pattern, and a multilocus probe would bind to multiple points on multiple chromosomes. The probe identified specific areas of the DNA with dark bands, as revealed by an X-ray (autoradiograph or autorad) of the membrane. Then a print of the polymorphic sequences could be compared to prints from other specimens. The interpretation of a sample was based on statistical probability.
At the culmination of the analysis, the genetic profile of Lynda Mann’s rapist was revealed, but when it was compared to R.B.’s sample there was no match. However, the work continued for the next “nail-biting” week on the semen removed from Dawn Ashworth, which was then compared to that from Lynda Mann. This time there
was
a match, but not the one expected. The samples matched each other, so while the same person had committed both crimes, neither sample implicated the suspect, R. B. Despite his confession, he was not their man.
The test was done again, with similar results, making R.B. the first person in criminal history to be exonerated by a DNA test. If not for science, Jeffreys would later say, an innocent person might have been found guilty and imprisoned.
The police who had worked long hours on the case wanted to challenge this finding, because it made no sense to them, but they were not able to do so. Jeffreys knew what he was talking about. The officers could only admit that they had made a mistake. Yet there was still the matter of the confession. When asked why he had admitted to rape and murder, R.B. said that he’d felt pressured. Yet he’d known unpublished facts about the crime scene, so the detectives surmised that he’d discovered the body before the police. (Others have suggested that during the interrogation, they inadvertently fed him the details, a common error.)
While the investigation continued, Jeffreys traveled to the FBI’s academy at Quantico to show them what the process involved, and at the age of thirty-six he became a renowned scientist. He would soon become famous all over the world.
Square One
Back in England, R.B. was released and investigators were determined to find the right perpetrator, so the men of Narborough and villages nearby within a certain age range, fourteen to thirty-one in 1983, were asked to voluntarily provide a blood sample. More than 4,500 men agreed to do it and most were eliminated via conventional blood tests (since DNA analysis was expensive and time-consuming). The goal was to ferret out any man who would not willingly submit to a test, because that man might have something to hide.
Each man came for his “blooding,” showed an identity card if he had one, and was interviewed. However, since the ID cards contained no photos, it was impossible to know if a man was really who he said he was. Some had passports and others had employment cards, but the process was less than airtight. If the subject was not a PGM 1+, type A secretor, he was free and clear. If he did have this blood type, his sample would be analyzed for a DNA profile. Yet, after all this processing, no new suspects turned up. Then, in September 1987, just the sort of suspicious incident the police had been expecting was reported.
A woman told them she had overheard a baker named Ian Kelly claim that he’d provided his own blood sample as a substitute for a fellow baker, Colin Pitchfork. The twenty-eight-year-old Pitchfork had a wife and child, but he was also a known thief and convicted flasher. When Pitchfork was questioned after the Lynda Mann murder, he claimed he had been babysitting his child while his wife was at school. This had checked out. When he heard about the community-wide blood test, he’d persuaded Kelly to go to the test site in his place. (He had approached three others, but they had refused.) He’d already received two notifications to show up, but said he was afraid that his past record would mark him as a likely suspect. He then fabricated a story that he’d already substituted himself to cover for another man, so he’d get into trouble if he showed up again. Kelly finally agreed and Pitchfork had given him a fake passport.
But Kelly had a big mouth. When he bragged about what he did to coworkers at a Leicester pub, one of them informed the police. That placed the spotlight dead on Pitchfork.
Before arresting him, detectives compared the signature from the blooding form, ostensibly signed by Pitchfork, with his signature on another form. There was no match. Despite its expense, the dragnet had worked: Pitchfork was a prime suspect. The police questioned other employees who had heard Kelly’s admission at the pub, and confirmed the story, so on September 18, they arrested Kelly for conspiracy to pervert the course of justice. He ratted out Pitchfork, acknowledging that his cover for a friend had delayed the investigation by eight months. He wasn’t going to get off lightly.
That night, the police arrested Colin Pitchfork at home. He confessed before he even got out the door, saying he had killed out of mere opportunity. About Lynda Mann, he said he’d initially decided to just flash her, but the excitement of the act had aroused him so much he decided to rape her. She’d run onto the dark path and he followed her, but then realized he would have to kill her or she’d identify him. He forced her into intercourse and then strangled her. Throughout all of his, his baby slept in his car. He returned and drove home, washed up, and then picked up his wife.
His tone grew contentious when he was discussing the second murder. The police insisted that he had anally penetrated Dawn Ashworth, but he claimed he had not. Nor did he hide her as thoroughly as he had hidden Lynda Mann, raising the possibility that someone else might have found her after the murder and sexually penetrated her. Or Pitchfork found the act too shameful to admit.
He confessed to attempting to take a third girl off into the fields to rape, but changing his mind. That girl had not told anyone. He also said he’d considered different ways of killing Ian Kelly to keep him from talking, but had feared this murder would be traced to him. The only time during his interview when he showed emotion was when he spoke enthusiastically about flashing. Otherwise, he was stone cold.
During his confession, he revealed a lot about himself. As a child, he’d felt inadequate and had been teased at school. At age eleven, he started showing his genitals to girls because he enjoyed the feeling of power it gave him. Eventually he was caught and had to go to court. He dropped out of school and found a job taking care of the handicapped, but eventually he needed the high he derived from exposing himself and went out to do it again. By this time he was married, and his wife was humiliated by his arrests. Still, she believed he’d eventually outgrow it. Colin found work as a baker and seemed to thrive in his job. He had an affair that nearly ended his marriage, but then he and his wife had a baby. After they changed their residence, he had another affair and conceived a child with the woman. He continued to look for opportunities to flash, and had nearly raped another girl. In essence, Pitchfork was a psychopath who looked for personal thrills and thought nothing of the harm he did to others.
To ensure that he would not try to recant what he had said, the police sent Pitchfork’s blood for DNA testing, and the results proved that his genetic profile was indistinguishable from that of both semen samples. He became the first person in the world to be convicted of murder based on Jeffreys’s method of genetic fingerprinting. On January 22, 1988, Pitchfork drew double life sentences, while Kelly received a suspended sentence for obstructing the investigation.
The Pitchfork case sparked headlines around the world, inspiring a great deal of attention from the law enforcement community. It seemed that a potentially foolproof method had been found for solving crimes in which biological evidence was crucial. The rush was on in many places to apply DNA technology to more crimes. Lifecodes, located near Westchester, New York, became the first private lab in the United States to offer RFLP testing for criminal incidents that involved biological evidence. Dr. Jeffreys forever altered the investigation of such crimes and he was knighted for his work. In 2004, he received a “Pride of Britain” award. Thankfully, the investigators on these cases were open to breakthroughs in science and the scientists were eager to apply their tools in the forensic arena. Although Pitchfork received a sentence that allowed for parole, he remains in prison at this writing.
Even as DNA revolutionized crime fighting in many countries, some law enforcement agencies continued to rely on older, less precise methods, and as a result many serial killers slipped through the cracks. Yet, concurrent with Jeffreys’s work in biology, a psychological approach was also gaining in popularity, and where low crime-lab resources precluded the use of DNA testing, there were often specialists in behavioral analysis. Because of this, one investigator in the Soviet Union made a bold move.
Sources
“An Interview with Sir Alec Jeffreys on DNA Profiling and Minisatellites,”
ScienceWatch.com
, retrieved December 4, 2007.
Jeffreys, A. J., V. Wilson, and S. L. Thein. “Individual-Specific ‘Fingerprints’ of Human DNA.”
Nature
37, 1985.