[MUSIC] Now, how are fingerprints created? Our skin is not smooth. It's covered in this minute pattern of ridges, and these are called friction ridges, and these are not accidental. These are very important to us. These friction ridges enable our hands to hold up objects. So if I didn't have friction ridges, I wouldn't be able to hold up this water bottle like this. It would drop out of my hand immediately. It's the pattern of the friction ridges that gives the pattern of the fingerprints. But what is a fingerprint actually made of? The material that is deposited is the excretion from the glands which are just below your skin, and these glands excrete a cocktail of natural chemicals - salts, fats, amino acids, proteins and water. And it's the deposit of these on the surface of some other object that creates the fingerprint. Now, let's compare fingerprints to DNA. With DNA technology, we can statistically calculate that no two people have the same DNA. Or, to be correct, we can statistically calculate that the likelihood of two people having the same DNA is minute and vanishingly small. Except of course, for identical twins, as we have discussed in the DNA lecture. Fingerprinting is not quite the same. Even though the early experts on fingerprinting did do statistical calculations, it's essentially experience. In more than a century of fingerprinting, no two people have been found to have the same fingerprints. Even identical twins do not have the same fingerprints. Their fingerprints may be very similar, but they are not necessarily identical. The reason that identical twins can have different fingerprints is that twins, identical twins, are identical at the moment of conception. Everything that happens after conception is not necessarily identical and can be different, and fingerprints, of course, are formed later. So the first principle of fingerprinting is about difference, and the First Principle is that no two fingers have the same prints, including identical twins. That is why when you're fingerprinted, they take all ten prints. The Second Principle of fingerprinting, which was pointed out by Mark Twain of course, is that fingerprints do not change during a lifetime. So, Mark Twain used the phrase "from the cradle to the grave". In fact, fingerprints form before you're in your cradle, before you're born, but obviously, that's not of great forensic use. And fingerprints remain after you're in your grave, after you're dead. In fact, fingerprints will survive as long as your skin survives. So even when your internal tissues are liquefying, you can still give fingerprints. Now, do fingerprints change? Fingerprints of themselves do not change, but fingerprints can be changed. So here is an example of the famous American gangster, he was number one most wanted, John Dillinger, and he knew the dangers of his fingerprints giving him away, so he attempted to destroy his fingerprints using concentrated acid. As you can see, he didn't succeed. Nevertheless, there are ways to get rid of your fingerprints and one way is if you're taking this anti-cancer drug, Capecitabine. So there was a gentleman who was taking Capecitabine because he was in remission from cancer. It's a anti-cancer drug. But he was in remission, and he travelled to the United States to visit friends and relatives. Now, when you enter the United States, you are fingerprinted. But one of the side effects of this drug is so-called hand and foot syndrome, which includes swelling of the tissues of the hand and foot, and his fingers had swelled so that his fingerprints had become indistinct and the officers at the passport control could not obtain his fingerprints. So this unfortunate gentleman was held for four hours until the immigration guys were convinced of his situation. So if you are taking this drug and you plan to travel to the United States, do make sure that you have a letter from your physician with you. I happen to know someone who has no fingerprint on one of her fingers, and this is one of my nieces. And when she was very small, she decided to investigate a rice cooker which was on. And she investigated it by putting her finger in the rice cooker, so the end of that finger was severely burned. And what amazes me, is how someone so small can make so much noise. Well, of course, she will, we took her to the doctor and her finger was treated and it's all fine now. But even to this day, she has no fingerprint on that finger. So yes, it is possible to remove your fingerprints, but this is a particularly painful way to do it. And in fact, showing up at immigration with no fingerprints at all is more suspicious than showing up with fingerprints. Now, fingerprints are being increasingly used in security and other areas to identify people, and therefore, it's obvious that criminals are going to try to find ways to get around fingerprinting. And one way that is being used is skin grafting. And this is just like a skin transplant - a doctor removes the skin from the end of the finger and grafts on skin from another part of the body, such as the feet. So this is not eliminating the fingerprint, but it's changing the fingerprint. The old fingerprint disappears and the new fingerprint will be from the friction ridges from whatever part of the body was used, such as the soles of the feet. So here's an example from a few years ago, 2005, when a man with a criminal record called Marc George entered the United States from Mexico. Now Mr. George, because of his criminal record, did not want to be recognized at the border. He knew he would be fingerprinted and therefore, he went in for the skin graft procedure. He got a doctor to graft skin from his feet onto his fingers. The mistake he made was to try to re-enter the United States before his feet had healed up properly and his limping gave him away, and he was identified and arrested. The doctor who carried out this procedure, a man called Jose Covarrubias, was tracked down. He was living in Harrisburg, Pennsylvania. He was tracked down a few years later and he was charged and ultimately sentenced to 18 months in prison. It's a relatively short sentence and that is because it could only be proved that Dr. Covarrubias had carried out this medical skin graft procedure, and there was no evidence that Dr. Covarrubias had been involved in any of Marc George's other activities. But this is going to be an increasing problem as the authorities rely on fingerprints to identify people; criminals will look for ways to get around that technology. The Third Principle is that the patterns can be classified, and this of course goes back to the work of Galton that we mentioned. The small features present in fingerprinting can be described in different terms, and you can see some of the terms here on this slide. On looking at them, you can see that some of the terms are clearly geographically inspired, and some appear to be inspired by the railways. In addition to these small features, the bigger pattern of the fingerprint can also be classified, and here you can see some of the classifications that fingerprint examiners use. [BLANK_AUDIO]
