1.9: A Brief History of DNA Typing

The concept of DNA was first discovered in 1869 when a Swiss scientist by the name of Johann Friedrich Miescher discovered what he called the nuclein, a phosphorus-rich substance from the nuclei of a cell; however, other scientists were slow to understand or accept the importance of DNA in its fundamental role in inheritance. The work of Friedrich Miescher was largely forgotten or ignored, but in 1919, Russian biochemist Phoebus Levene published the rudimentary discovery of what he termed the tetranucleotide structure of DNA based on the Guanine, Cytosine, Adenine, and Thymine model (G-C-T-A-G-C-T-A etc.). In the 1940’s, Austrian biochemist Erwin Chargraff conducted research to determine if there were any differences in the DNA of varying species. He discovered the nucleotides of different species were not in the same order as Levene had thought. He also concluded that almost all DNA maintains certain properties, no matter what organism it came from, even with varying composition. This led to the discoveries of James Watson and Francis Crick in the 1950’s. They proposed the double-helix structure of DNA and discovered that it was an extraordinary molecule skillfully designed to carry out the task of controlling the genetic traits of all living cells, plants and animals.

A forensic application of DNA was not even considered until the discovery of two teenage girls who were found raped and murdered in the United Kingdom in 1983. The body of 15-year-old Lynda Mann, a schoolgirl from Narborough, a large village in Leicester, England, was found on a walking path. She had been strangled and raped. There were no witnesses or clues, and no investigative leads as to the identity of the suspect. Three years later, another teenage schoolgirl, Dawn Ashworth, was strangled and raped and her body found on a path in the woods less than a mile from where Lynda Mann’s body was discovered. The constabulary was convinced the same person was responsible for both crimes, and they increased their efforts to find the person responsible for these hideous crimes. Richard Buckland, a 17-year-old-youth, was the prime suspect. During interrogation, he confessed to the murder of Dawn Ashworth, but not to the murder of Lynda Mann. This presented a problem for the investigation, and the police were determined to link both murders to the same suspect. The lead detective had heard of work being done at Leicester University by Professor Alec Jeffreys to determine if certain diseases on the human body could be linked to an error in the double-helix profile of a person’s DNA. While doing this research, Professor Jeffreys had developed a blood test that resulted in far better genetic information than was previously available. The lead detective called Professor Jeffreys and asked if his test could identify a person using the DNA recovered from semen found in the clothing of both victims. Professor Jeffreys agreed to test this theory. He developed an enzyme from the semen that matched and determined the genetic profile matched only 10% of the male population. Interestingly, neither sample matched the genetic profile of Richard Buckland. His confession was false. It is remarkable to think that the very first application of DNA in a criminal investigation was to prove the innocence of a suspect who had confessed. In a call for compassionate support from the community, the Leicestershire Constabulary requested all 6,000 males in the three small villages surrounding the crime scenes to submit voluntary blood and saliva samples. Professor Jefferys and his team typed every sample for a genetic profile, but none matched the earlier samples recovered from the crime scenes. In 1987, Ian Kelly boasted to friends at his local pub that while working in a village near Leicester, he had been approached by a baker by the name of Colin Pitchfork and was paid 200 pounds to present Pitchfork’s passport to the police and to provide his blood and saliva samples in place of those of Colin Pitchfork. A person who overheard the conversation reported this information to the police. Ian Kelly was brought in for questioning and he provided the same story. The police therefore arrested Colin Pitchfork for the deception and obtained blood and saliva samples. The DNA from these samples were matched to the semen samples recovered from both victims. He was tried and convicted of both murders and received two Life sentences. In 2025, Colin Pitchfork lost his bid for parole by a decision of the High Court and he remains in prison at the time of this writing. In his own words, Professor Jeffreys said that he had never envisioned the use of his research on the human genome to have such an influential impact on the culpability or innocence of persons who are accused of a crime. It was without a doubt the most fortuitous telephone conversation between a lead police detective and a professor perhaps in the history of the forensic sciences.

Your author recommends the reader conduct research into what compelled nearly 6,000 men to voluntarily submit their blood and saliva to law enforcement. It is an interesting example of community compassion, peer pressure, and honorable endeavor.