[MUSIC] I said at the beginning that DNA technology has brought fundamental changes to forensic science and changed the way that convictions can be brought for criminals. But DNA technology has also done something else. It has also given us a very powerful technique to prove that people are innocent. So let's go back to the first case where DNA was used, and we will see that the first person who was investigated using DNA profiling was not found guilty; he was proven innocent by DNA technology, even though he had confessed to the crime. So let's go back to a small town called Narborough in England in 1983. And the body of a teenager, she was just 15, called Lynda Mann, was found in the countryside outside the town, and she'd been raped and murdered. In 1983, technology only allowed forensic scientists to show that the killer had blood type A, and that was all. In 1986, a second victim, also 15, was found - Dawn Ashworth. And then something odd happened. A local guy, a young man called Richard Buckland, confessed to the murder of Dawn Ashworth but he insisted that he had not murdered Lynda Mann. Well, because of the similarities in the way that the two murders had been committed, the local police were convinced they'd been done by the same person, so they wanted some way to show that Richard Buckland had been responsible for both killings. So Narborough's not that far from Leicester and they asked Alec Jeffreys to help. So they supplied him with samples from both crime scenes and a sample from the confessed killer of one Richard Buckland, and Alec Jeffreys did the DNA analysis, and got a very surprising result. The DNA of the suspect did not match the DNA from either crime scene. Richard Buckland had killed neither of them. Well, why had he confessed? We can speculate about the reasons why he confessed, but people do actually confess to crimes they didn't commit, so any confession really does have to be corroborated with some other evidence. Well, Alec Jeffreys was able to give the police one useful piece of news - they were right in saying that the same man had committed both murders. Well, in an investigation a little reminiscent of the Griffiths case back from the 1940s, which we'll talk about in another lecture, the local police decided to do DNA screening of all men in that area. So they're assuming that the murderer was a local man, but they were able to narrow down the search because they knew that the killer was blood type A, so they only had to do DNA screening of everyone with blood type A, and that added up to over a 1,000 men. And in all those samples, there were no matches at all. Then there was a break in the case. A woman in a pub overheard a conversation, and in that conversation, a local man called Ian Kelly was saying that when he gave his blood sample for the DNA work, he had done it under the name of a friend and colleague called Colin Pitchfork. Which means that the blood sample, the DNA sample, labelled Colin Pitchfork had actually come from Ian Kelly. The woman told the police, the police arrested Colin Pitchfork, and he was obliged to give a genuine sample. And of course, as you would expect, his DNA matched the DNA from the crime scene. Well, with that evidence in place, Colin Pitchfork confessed to both murders. And that's quite interesting, because he confessed even though this was a brand new, untested technology. Well, he was found guilty, sentenced to life in prison, to serve a minimum of 30 years. And at the time of recording, he's still in prison. [BLANK_AUDIO]