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The godfather of DNA fingerprints: How Alec Jeffreys revolutionized solving crime

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Michael Whyte
Crime Scene Officer and Fingerprint Expert with over 7 years experience in Crime Scene Investigation and Latent Print Analysis. The opinions or assertions contained on this site are the private views of the author and are not to be construed as those of any professional organisation or policing body.
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IT’S now 30 years since Alec Jeffreys invented the genetic fingerprinting that has solved thousands of crimes and helped many paternity cases. The dream of every scientist is to experience a once-in-a-lifetime “eureka moment”. For Professor Alec Jeffreys that remarkable time arrived on September 10, 1984, in his laboratory at Leicester University.

While studying the DNA of three people he realised that there were enormous differences between each sample. It was a breakthrough which would revolutionise crime-fighting. Tiny shreds of DNA such as a speck of blood could be used to link a suspect indisputably to a crime scene. From that time no unconvicted killer could sleep soundly at night.

“We were getting extraordinarily different patterns of DNA,” recalls Sir Alec, who received a knighthood for his work a decade later. “The penny dropped and I realised we had genetic fingerprinting. It opened up a whole new area of science. My life changed that Monday morning. “Within seconds it was obvious that we had stumbled upon a DNA-based method for identification. It really was an extraordinary moment.”

Sir Alec, who grew up in Oxford, was inspired to become a scientist when his father gave him a microscope and chemistry set. He loved making explosions and was splashed in the face with sulphuric acid when one living-room experiment went wrong. He still has the scars, which he regards as “a badge of honour” but covers them with a beard. After studying biochemistry at Oxford University but finding it “a bit dry” he switched to genetics. At Leicester, from 1977, he was given free rein to follow his hunches about the great diversity of human DNA.

Sir Alec could barely contain his excitement when he made his discovery. “I was running around with blood stains making imaginary crime scenes,” he says. Immediately he and an assistant wrote a list of all the possible uses. However he reveals that some colleagues did not initially share his enthusiasm or realise the scope of DNA-based identification.

Sir Alec, a father of two, says: “When we first gave a talk on DNA fingerprinting and speculated about what we could use this for, such as catching rapists from semen, people fell about laughing. They thought I had lost my marbles. “It sounds bizarre now because it’s so blindingly obvious that you can use DNA for police work but believe me back in the 1980s it was regarded as complete hokum.”

The story of how his DNA breakthrough was first used to solve a murder is to be the subject of a new ITV drama. Filming of Code Of A Killer is due to start this month. Sir Alec, 64, who still works at the university, admits he envisaged DNA fingerprinting would only be a crime-fighting tool of “absolutely last resort” after all other detective work had failed. In fact the search for DNA at a crime scene, such as on a discarded cigarette, is now routinely the first step towards tracing the prime suspect. Worldwide, the details of 50 million people are thought to be stored on DNA databases. Here we look at the technology and some of its uses.


DNA is the hereditary material in the human body and is found in everything from skin and blood to saliva and strands of hair. It’s also in urine, semen and tears. We share 99.9 per cent of our DNA (Deoxyribonucleic acid) with other people but it’s the tiny remaining fraction that sets us apart. DNA is like the body’s unique signature and has also been described as a genetic code. There are even subtle differences in the DNA of identical twins.

In police forensics work DNA is extracted from human cells. At first the vast differences between people’s DNA were not fully appreciated. But it soon became apparent there were many millions, making it the perfect crime-solving weapon. The chances of a mistake if the sample is correctly tested and handled is minute. In the early days of the technique relatively large amounts of DNA were required to prove a person’s identity but as skills have improved it can now be extracted from the tiniest speck of blood.


The first use of DNA fingerprinting was to settle an immigration dispute. Christiana Sarbah had been fighting for two years to prove to the Home Office that she and her boy Andrew were indeed mother and son. The case in 1985 established that DNA fingerprinting, also known as genetic profiling, had reliable practical uses and soon detectives were beating a path to the scientist’s door.

The first murder conviction was in 1988 following the rape and killings of two young girls, Dawn Ashworth and Lynda Mann, in the Enderby area of Leicestershire. Police had a suspect who had confessed to one murder and they decided to use genetic fingerprinting to establish his guilt for both. Against all expectation he was found to be innocent. Detectives who had samples of DNA from the crime scenes then tested 5,000 men in the area. No match was found until local baker Colin Pitchfork was overheard boasting that he had persuaded a friend to give a sample on his behalf. A DNA test showed he was the killer.

Genetic profiles can survive on clothing and other items for centuries, allowing police to delve deep into the past to solve “cold cases”. The use of familial DNA – using a relative’s sample to narrow down the list of suspects – is another step. DNA profiling showed that bones of a man called Wolfgang Gerhard who drowned in Brazil in 1979 were actually the remains of the Nazi Josef Mengele. Known as the Angel of Death he was responsible for the deaths of 400,000 people in concentration camp gas chambers. The technique was also used to prove beyond doubt that Dolly the sheep was a clone of the original.

Source: Express UK – September 6 2014

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