[MUSIC] In a court case, when someone's being tried for a criminal offence, there are actually two things that have to be demonstrated. It's not sufficient to demonstrate that a criminal action was committed. It's also necessary to demonstrate that there was an intention to commit the criminal action. If there's a body lying on the floor with a knife sticking out of their neck, or a bullet hole through their head, then it's very obvious that something bad has been done, but it's also necessary to determine the intention. So in legal terms, the two things that have to be demonstrated, the first one is Actus Reus, a guilty action. The second one is Mens Rea, which literally means the guilty mind or the intention. Now, forensic science is very good at determining one of these, the Actus Reus. Because the physical evidence, the biological, the chemical evidence that can be acquired at the crime scene, can allow you to indicate that what has been done and who did it, often very well. But forensic science is not very good at determining Mens Rea, the intention, and that is because Mens Rea is concerned with what is going on inside someone's head and not in the physical world. Here's an example. The gentleman on the left is Mr. Dick Cheney, the former Vice President of the United States. The gentleman on the right is a friend of his, Mr. Whittington, a lawyer from the state of Texas. Back when Dick Cheney was Vice President, one day he went out hunting with his friend Whittington in the woods in Texas, and they were hunting quail. So what we understand is that Dick Cheney was going ahead through the woods, and he saw some movement in a bush so he turned and he fired because he thought there were quail there. Unfortunately, it wasn't quail that were causing the movement of the bush, it was his friend Whittington. So he shot his friend Whittington. Now, there was never any question that Dick Cheney did it, and he never tried to hide the fact that he did it, but forensic science would've been very well placed to show that he did it. You could look at the footprints in the ground. You could look at the fingerprints on the gun. You could pull the pellets out of Mr. Whittington, etc., etc. And forensic science would've made a very strong case to show that Cheney did it. But why did Dick Cheney do it? Was it really an accident? Or did he have some other motive? [BLANK_AUDIO] It was very clear from the case that it was a pure accident. But if you think about the case from the point of view of forensic science, none of that forensic evidence would've been able to tell you about whether it was an accident or not, because that is entirely within the mind of Mr. Cheney, and typically, this is the case. Forensic science will tell you about Actus Reus but not about Mens Rea, though later we'll have a case study where this is not true and that forensic science could indicate the true intention of the criminal. Now, we've talked about science, but what is forensics? Well, a very simple definition of forensics would be to say that it is the application of science to law. But actually, law is a very broad term because it includes civil and commercial law, where there typically is no application of forensics. So it may be easier to narrow it down as the application of science to criminal justice involving the analysis of the physical evidence, the chemical evidence, and the biological evidence from the crime scene and elsewhere. As we've said, forensic medicine, distinct from forensic science, deals with crimes involving a human body. [BLANK_AUDIO] Now, one thing forensic science can help us do is to enable us to reconstruct what happened. We come to a crime scene, maybe it's someone's apartment. Things are smashed. There's blood on the floor. There's marks and stains etc. And forensic science can look at all those marks and stains and all those signs, all that evidence, and build a story as to what happened to create that scene. So here on the left, there's a crime scene. Here on the right is a suspect, and these are some of the evidence that we can use. You might find fibres from the suspect's clothes. You might find hair. There's broken glass here, so you might find blood. There may be fingerprints, and if the ground is dirty, then you might find shoe prints. Similarly, you can look at the suspect. You might, for instance, find broken glass from the window embedded in the suspect's clothes. If there's a carpet in the room, you may find fibres from the carpet on the suspect. And you might find paint flakes, for instance, in his clothes as well. So, forensic science can help us to reconstruct what happened and it can also help us to link the suspect with the crime scene. Forensic science and also forensic medicine can also help us decide what is the charge involved in the case. In this very sad incident here, this young lady had a baby, but she didn't want the baby and what she did was to dump the baby down a garbage chute. Of course, the body was found, the mother was traced, and she was investigated. You would, if you dump a baby down a garbage chute, the baby is likely to die and the baby was dead when it was found. So the charge should be a charge of murder because essentially, she would have killed the baby. But of course, the body of the baby is sent for examination by the pathologist, and in this case, the pathologist was able to determine that the baby was very premature, and most likely, highly probably, had not been born alive. Therefore, this unfortunate mother had not dumped a living baby down the garbage chute, but had dumped a dead body down the garbage chute. That is still a criminal offence, but is so much less serious than a charge of murder. So, here's a case where forensic medicine has reduced the charge from a serious one to a much lesser one. It can also go the other way. This is a case from Singapore in April of 1972. And this picture shows the railway line that used to be linking Malaysia with Singapore. And in this incident, the train was coming in from Malaysia along the line. The driver noticed something lying on the tracks, but of course, trains don't stop that easily and this train ran over the object before it could stop. The driver got out, came back to investigate and discovered that he had run over a human body. Well, why would a body be on the tracks? It's possible that it's a suicide. It's also possible that it's a terrible accident. And if it's either a suicide or an accident, then the investigation will be wrapped up relatively quickly and come to an end. But a specialist in forensic medicine was asked to come down to the railway line, it was Chao Tzee Cheng himself. He was asked to come down to the railway line to examine the body, and he noticed that the condition of the body was not what you would expect from a suicide or accident. And it was particularly because of what we call the blood spatter. In a living body, the heart is beating, the arteries are pressurized. So if an artery is severed, for instance by being run over by a train, the blood is going to spurt out in considerable quantity. If the body is already dead, the heart is not beating, the arteries are not pressurized, so if the arteries are severed by the train wheels, then the blood is not going to spurt out and there will be much less blood at the scene. And Chao Tzee Cheng noticed that was the case. There was not enough blood at the scene to be consistent with a living body. So, he said this body was already dead when it was put on the track. Therefore, the police organized a full investigation of the case. Clearly what had happened is, the boy had been murdered and then his body had been put on the track to make it look like a suicide or an accident, when it was, in fact, a murder. The investigation indeed led to the apprehending of the murderer and his subsequent conviction in court. And it turns out that this poor boy had been murdered for the few dollars that he had in his pocket. [BLANK_AUDIO]
