[MUSIC] Well, DNA technology has enabled a lot of cold cases. These are old cases where the investigation didn't reach a conclusion. These cold cases can be re-opened and re-investigated, provided that the evidence from the crime scene has been properly preserved. These can be re-investigated with the help of DNA databases, so many countries nowadays have databases of DNA taken from known criminals. So if someone committed a crime long ago but were never caught, committed a crime later and their DNA was taken, then the DNA from that old case can be compared to the DNA in the database, and if they're in the database, up pops their name. Of course, it only works if the culprit is in the DNA database, but many criminals will commit more than one offense, and this is how they can get caught. So, here's an example. This is Lesley Molseed, a young girl who was sexually assaulted, stabbed to death, her body left out on the Yorkshire moors, back in 1975. This man here, Stefan Kiszko, was convicted wrongfully of the crime, and even though he was innocent, he spent 16 years in prison. Okay. It took that long before his name could finally be cleared and he could be released. Well, the evidence from the crime scene had been preserved, and when the technology permitted, it was analyzed using DNA, and the DNA extracted was compared to the DNA in the national database, and up came the name of a local man called Ronald Castree. He had a minor criminal record, but it had put him in the database. He was charged with the sexual assault and murder of Lesley Molseed and brought to trial. Problems, though, this is a trial in 2006 for a crime that occurred in 1975. Okay, more than 30 years before. So the first problem is that most of the original witnesses are dead, so the trial had to rely on notes taken at the time. One of the last living witnesses who visited the crime scene was a retired forensic scientist called Ronald Outteridge, and here we have problem number two. Is there proof that the sexual assault and the murder were done by the same person? So as Ronald Outteridge said in the case, "To do that it would be necessary to prove that the semen was deposited during the murder of the little girl and I found no evidence to show that was the case. It might have been, it might not." So what is being suggested here, is that Lesley Molseed had been abducted and sexually assaulted and then released, and had continued walking home and then had been abducted a second time and murdered. So it comes down to what is considered to be reasonable. Did the jury think that this second problem here amounted to reasonable doubt? And the answer is no. Ronald Castree was convicted and sentenced to 30 years in prison. [BLANK_AUDIO]