[MUSIC] [MUSIC] We don't know the name of this victim; he was given the name "Adam" by the police during the investigation. He was found in 2001 on the bank of the River Thames, in central London. It wasn't a complete body, it was only the torso. So the head was missing, the arms were missing. They had been cut off and they'd been cut off very professionally with a very sharp knife, and the blood had all been drained from the body. The body was wearing a pair of shorts and that is it. That is all that the forensic scientists had to work with - a torso and a pair of shorts. And what is remarkable is that forensic scientists, just with that evidence, were able to advance the investigation a long way. Well, the obvious thing to look at is the shorts. The shorts, like so many items of clothing, were made in China. But they were able to track down the manufacturer. They were able to identify which batch of shorts it was, and these shorts had been sold in West Germany. Investigation of the torso involves examining the stomach contents, and there were some strange things in the stomach. It contained food. It contained pollen. Now pollen is released into the air by plants all the time, and naturally a lot of it gets inside us, and pollen under the microscope can be identified, you can tell which plant it comes from, and the pollen in the boy's stomach was characteristic of Northern European plants. And then there were some very strange things in his stomach. There was clay, there was calabar beans. Now, calabar beans are toxic and they are not native to Europe, they come from Africa. And there were also gold particles in the stomach. Now, the presence of these last three items is very significant indeed. These items are connected with African black magic. So, it was suspected that this was not an ordinary murder. It was believed that this boy had been smuggled to Europe, to West Germany specifically, and then shipped to London to be used in black magic, specifically human sacrifice. Now, what else can we do? How can we further advance this investigation? How can we find out, for instance, where Adam originally came from? And it was elemental analysis that achieved this. We've all heard the expression, "you are what you eat", and it is literally true. Okay, your body is made up of the elements that you eat as part of your diet. Now, let's look at bones. Bone is basically calcium phosphate in a protein matrix. Everybody's bones contain large amounts of calcium, and that calcium comes from your diet. And this is why, particularly when you are growing up, it's important to have a good amount of dairy products because that is an excellent source of calcium. But, other metals would also be incorporated into your bones if they are present in your diet. Now, people who live in traditional societies tend to eat food that is grown in their neighbourhood, in their backyard, on their farm. That food will contain minerals from the local soil, so if the local soil is particularly rich in a particular element, then the food those people eat will tend to be richer in that element, and this will be reflected in the chemistry of those people's bones. So, for instance, if the soil in a particular region is higher in levels of say, strontium, or copper, or lead, then those people's bones will be higher in quantities of those three elements compared to people from a different region. So, this is what was done. Adam's bones were analyzed for these trace elements. And indeed, he had a little more of these elements than normal. Now, based on the idea of human sacrifice and black magic, it was believed that he came from somewhere in West Africa because that is where these beliefs come from. But West Africa is an enormous place and there's millions and millions of people there. But the trace element in all of this was able to narrow it down. Investigators travelled to different places of West Africa, took samples of the soil, samples of bones, and compared the trace element composition of both samples to the trace element composition of Adam's bone, and that narrowed the search down to a small region of Nigeria. So forensic science, in this case, didn't identify the murderer, but it certainly told the investigators where they should be looking. So, what have we learnt in this lecture? We have seen how spectroscopic methods work, whether they are based on emission or like atomic absorption spectroscopy, on absorption. So, we know how they work and we know their basis in the structure of the atom. We've looked at the EDX technique, which uses x-rays and we have seen how that can be a very, very powerful technique for forensic scientists when it's combined with scanning electron microscopy. And we've also had a quick look at the technique called Neutron Activation Analysis. So overall, by understanding the structure of the atom and how electrons can move between their energy levels, we understand how forensic scientists can very accurately and reliably determine the elemental composition of a given sample, even to very, very low levels of a particular element, and now we understand how this is a very, very powerful technique. [BLANK_AUDIO]
