[MUSIC] There are many crimes with no witnesses. This is a crime from 1948, and it concerns a three year old girl called June Devaney, who had been in hospital with pneumonia. She was recovering, but in the very early hours of May 15, the nurses noticed that her cot was empty. Under the cot was an empty water bottle, that's a bottle that would contain medical sterile water. And prints from adult feet, stocking-ed adult feet, could be seen going from the cot to the door. There was a search of the hospital and the hospital grounds, and a couple of hours later, her dead body was found in the grounds and she'd been killed by being smashed against a wall. So what evidence have we got? Well from the footprints, you can see the pattern of the weave of the socks, but more importantly on that water bottle, there were fingerprints. Well, who's likely to handle a water bottle in a hospital? Well, doctors, nurses, hospital staff. So these all had to be fingerprinted, and it was found the fingerprint didn't belong to them. Then patients, visitors, ambulance drivers, fingerprinted, also eliminated. That was 642 sets of fingerprints in three days. And remember, this is 1948. All these has to be done by fingerprint examiners. There's no electronic databases available. Second, they moved on to anyone familiar with the hospital. Another 200 sets of prints, again, no matches. The investigators, therefore, decided to fingerprint every male in the town. Every male in this town of Blackburn over the age of 14 years. This is a similar strategy to the one used in our DNA lecture, in the Colin Pitchfork case. This is a huge undertaking, 50,000 fingerprints. And you run up against a problem, because how do you actually know who lives in a town? Well, one way of course is to walk around the town, knocking on every door, but you can't guarantee that every time you knock a door, you're going to get an answer. Another way is to look at the tax records, but then not everybody pays tax, so this is not perfect. You can also look at the electoral register, but then not everyone is registered to vote, so this is also imperfect. However, this was Britain in 1948, and in that post-war era of austerity, there was rationing. Even though not everybody answers the door, not everybody pays tax, not everybody votes, everybody's got to eat, and the only way to get food is using coupons from ration books. So when the next issue of ration books were made, police were able to get the list of names. And sure enough, there was a name on that list that hadn't shown up on any other lists. There was former soldier called Peter Griffiths. He was fingerprinted and his fingerprints matched the fingerprint on the water bottle. He was found guilty of the murder and hanged. [BLANK_AUDIO]