[MUSIC] An additional technique for bodies that are in this stage is to use what is called forensic entomology. Entomology is the study of insects. So, how can we use insects to determine the time of death? Well, our dead body is lying somewhere outdoors and it's starting to smell and it's detected very, very quickly by insects, and the females, of course, are always looking for a good place to lay their eggs, and there's nowhere better than a dead body. They can lay their eggs on the dead body; when the eggs hatch, their children come out, that's the maggots, then their children are assured of a really good supply of food, so that they can develop and produce the next generation of blowflies. The life cycles of these creatures are usually fairly regular. So if you can find a maggot off the corpse, and you can estimate how old that maggot is, you've got a good estimate of the time of death. But it has to be done right, because each kind of insect has it's own life cycle, with it's own timing. The first thing you have to do is to know the species. This is not so easy from a maggot. So, what is typically done is that the maggots are collected from the body, from the corpse, they are taken back to the laboratory and they are reared to adulthood. When you have the adult it is much easier to identify the species. When you identify the species, then of course, you know what the life cycle is. So, when you take your maggot back to the laboratory and you rear it to adulthood, you also time how long it takes to reach the adult stage, and then you can back calculate, from the length of the life cycle, how long it had been on the body. So here, for instance, is the life cycle of the blowfly. It starts out as an egg, the egg hatches to give a little maggot called the 1st Instar, then it changes to the bigger 2nd Instar, and then the third Instar maggots. And then when they are fed sufficiently, they will turn into a pupa and they will undergo their metamorphosis, and they will emerge as the adult and the life cycle of the blowfly has gone round once. Sometimes this technique is very, very powerful. An example comes from this case, from back in 1964, involving a man called Peter Thomas. In this case, some boys had gone down to the local woods because they wanted to collect worms so they could go fishing. And they found more than worms. They found the dead body of Peter Thomas absolutely covered in maggots. So of course, the police came, and the police looked at the body, and they thought that it had been there for maybe six to eight weeks. But a forensic expert, Professor Keith Simpson, was called in. And Simpson took a look, and he took a look at the maggots, and he disagreed with that six to eight week estimate and he said, "At least nine or ten days, not more than 12 days." And when they did the back calculation, that works out as June the 16th or June the 17th of 1964, and these dates proved to be extremely important during the prosecution. Now, the police had identified a suspect in the case, and this was a man called William Brittle who had had some financial dealings with Peter Thomas, and there was some bad result from this. So it was suspected that Brittle had murdered Thomas in some kind of dispute over money. So when this went to trial, one of the issues was the time of death. Keith Simpson has said that Thomas was dead on June the 16th or June 17th. Very importantly, Brittle had no alibi for that time, but he had a good alibi for dates after that. Well, the defense came up with three witnesses who claimed they had seen Peter Thomas alive and well on June the 20th or 21st, several days after Simpson says he's dead. So here on one hand, you have the maggots. On the other hand, you have the eyewitnesses. But the defense went a bit too far, they called their own entomologist and they asked their own entomologist to testify based on the maggot evidence. And that's where it went wrong for the defense, because their expert turned out to agree with Simpson, saying the man was dead on the 16th or the 17th. Well, who're you going to believe? Are you going to believe the eyewitnesses, or are you going to believe the maggots? Well, in this case, the jury preferred to believe the maggots, not the eyewitnesses. On the other hand, forensic entomology can also let you down. Let's look at the case here of a young girl called Danielle van Dam who was murdered back in 2002. She was about 7 years old. So she was last seen alive by her parents on the evening of February the 1st, when her mother put her to bed. The next morning, she was missing. So from February the 2nd she had disappeared. Suspicion fell on a man called David Westerfield who lived nearby, and he had gone off on a trip into the desert. This is in California, he'd gone off into the California desert in his RV for a few days, and only came back home on February the 5th. As soon as he came back, he was essentially placed under police surveillance. So from February the 5th, the police were watching him, and you really can't get a better alibi than being watched by the police. It took a long time for Danielle's body to be found. It was finally found on February the 27th, so this is more than three weeks after her disappearance. It was up in the California mountains. Obviously by this time badly decomposed, and also, it had been attacked by animals, maybe coyotes or something. In fact, one of the ways they had to use to identify the body was to fingerprint it. So the fingerprint, even though the tissues were decomposing, they were able to get a fingerprint off the skin of the finger. Now a key question was, when did Danielle die? When was her body dumped in the mountains? Well, here's the calendar of January and February, and they consulted a number of experts, particularly forensic entomologists, to get estimates of when her body was placed in the mountains. And what I've done here is to highlight in red those few days from February the 2nd to the 5th, when David Westerfield was on his trip to the desert. So the first expert made this estimate here, that the body had been there since the second half of January. Well, of course this is impossible because, as you know, Danielle was tucked in by her mother on February the 1st. This expert conceded that maybe he could stretch the dates through into the first week of February, which includes the time of Westerfield's desert trip. A second expert, looking at the entomology, put it from the 12th to the 23rd of February, basically the second half of February which is time when Westfield was under police surveillance. The third expert, a slightly earlier time frame, but still during that period of police surveillance. The fourth expert pinned it down to a few days, again, it's in middle February. And another expert, again, the late part of February. So when you see five experts in the same area giving estimates that are so widely varying, this does not lend very much credibility to the subject. And so the investigators, of course, also consulted medical examiners, and the medical examiners gave this estimate here, from the first of February to late February. So, as I said at the very beginning, it's very difficult to give a very accurate estimate, and that's why the range they've estimated here is so big. So, what went wrong? Why is it that the entomologists' estimates are all over the place? Well, there are other variables that have to be taken into account. One thing is the weather. This is up in the mountains. The weather in the mountains can be very variable. So maybe the weather at the weather station, which was some miles away, was somewhat different from the weather where Danielle's body was left, and therefore it's not possible to make an accurate estimate. There's also the possibility of micro-climates. Anyone who's been in the mountains knows that the south facing side of the mountain, the weather is quite different, it's distinctly warmer to the north side of the mountain. And in fact, in mountainous country, you'll only have to go a few hundred metres and you can experience these changes. Another factor is whether the body was covered or not. If the body had been covered, then it would delay when the insects would find it, and this was never really resolved. And then again, of course, there is the possibility that actually David Westerfield is innocent and that the entomologists have got it right. Well, in the end, David Westerfield was found guilty and he was sentenced to death by lethal injection, and at the time of recording, he is still in prison awaiting that sentence to be carried out. So presumably, the jury believed the evidence of the medical examiners and discarded the opinion of the entomologists, and they also considered other evidence such as the fingerprints, some blood spots, and the hair from the van Dam family dog in the Westerfield RV as indicating guilt. But the story very clearly illustrates that making these estimates can be very, very difficult indeed. [BLANK_AUDIO]
