3 - 3 - Week 3A - 3 Decomposing Bodies II (Forensic Entomology) (11 50), kryminalistyka, introduction to forensic ...
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[MUSIC]An additional technique for bodies thatare in thisstage is to use what is called forensicentomology.Entomology is the study of insects.So, how can we use insects to determinethe time of death?Well, our dead body is lying somewhereoutdoors and it'sstarting to smell and it's detected very,very quickly by insects,and the females, of course, are alwayslooking for a good placeto lay their eggs, and there's nowherebetter than a dead body.They can lay their eggs on the dead body;when theeggs hatch, their children come out, that'sthe maggots, then theirchildren are assured of a really goodsupply of food, sothat they can develop and produce the nextgeneration of blowflies.The life cycles of these creatures areusually fairly regular.So if you can find a maggot off thecorpse, and you can estimatehow old that maggot is, you've got a goodestimate of the time of death.But it has to be done right,because each kind of insect has it's ownlife cycle, with it's own timing.The first thing you have to do is to knowthe species.This is not so easy from a maggot.So, what is typically done is that themaggots are collected from the body, fromthe corpse, they are taken back tothe laboratory and they are reared toadulthood.When you have the adult it is much easierto identify the species.When you identify the species, then ofcourse, you know what the life cycle is.So, when you take your maggot back to thelaboratory and you rear itto adulthood, you also time how long ittakes to reach the adult stage,and then you can back calculate, from thelength ofthe life cycle, how long it had been onthe body.So here, for instance, is the life cycleof the blowfly.It starts out as an egg, the egg hatchesto give a little maggot called the 1stInstar, then it changes to the bigger 2ndInstar, and then the third Instar maggots.And then when they are fed sufficiently,they willturn into a pupa and they will undergotheir metamorphosis,and they will emerge as the adult andthe life cycle of the blowfly has goneround once.Sometimes this technique is very, verypowerful.An example comes from this case, frombackin 1964, involving a man called PeterThomas.In this case, some boys had gone down tothe localwoods because they wanted to collectworms so they could go fishing.And they found more than worms.They found the dead body of Peter Thomasabsolutely covered in maggots.So of course, the police came, and thepolice looked at the body,and they thought that it had been therefor maybe six to eight weeks.But a forensic expert, Professor KeithSimpson, was called in.And Simpson took a look, and he took alook at the maggots,and he disagreed with that six to eightweek estimateand he said, "At least nine or ten days, notmore than 12 days."And when they did the back calculation,that works outas June the 16th or June the 17th of 1964,and these dates proved to be extremelyimportant during the prosecution.Now, the police had identified a suspect inthe case, and this was a man calledWilliamBrittle who had had some financialdealings with PeterThomas, and there was some bad result fromthis.So, it was suspected that Brittle hadmurderedThomas in some kind of dispute over money.So when this went to trial, one of theissues was the time of death.Keith Simpson has said that Thomas wasdead on June the 16th or June 17th.Very importantly, Brittle had no alibi forthat time,but he had a good alibi for dates afterthat.Well, the defense came up with threewitnesses who claimed they hadseen Peter Thomas alive and well on Junethe 20th or 21st,several days after Simpson says he'sdead.So here on one hand, you have themaggots.On the other hand, you have theeyewitnesses.But the defense went a bit too far,they called their own entomologistand they asked their own entomologist totestify based on the maggot evidence.And that's where it went wrong for thedefense, because their expert turned outto agree with Simpson, saying the man wasdead on the 16th or the 17th.Well, who're you going to believe?Are you going to believe the eyewitnesses, orare you going to believe the maggots?Well, in this case, the jury preferredto believe the maggots, not the eyewitnesses.On the other hand, forensic entomology canalso let you down.Let's look at the case here of a younggirlcalled Danielle van Dam who was murderedback in 2002.She was about 7 years old.So, she was last seen alive by her parentson theevening of February the 1st, when hermother put her to bed.The next morning, she was missing.So, from February the 2nd she haddisappeared.Suspicion fell on a man called DavidWesterfield who lived nearby,and he had gone off on a trip into thedesert.This is in California,he'd gone off into the California desertin his RV fora few days, and only came back home onFebruary the 5th.As soon as he came back,he was essentially placed under policesurveillance.So from February the 5th, the police werewatching him, and youreally can't get a better alibi than beingwatched by the police.It took a long time for Danielle's body tobe found.It was finally found on February the 27th,sothis is more than three weeks after herdisappearance.It was up in the California mountains.Obviously by this time badly decomposed,and also, it had been attacked byanimals, maybe coyotes or something.In fact, one of the ways they had touse to identify the body was tofingerprint it.So the fingerprint, even though thetissues were decomposing, theywere able to get a fingerprint off theskin of the finger.Now a key question was, when did Danielledie? When was her body dumped in themountains?Well, here's the calendar of January andFebruary,and they consulted a number of experts,particularly forensicentomologists, to get estimates of whenher body was placed in the mountains.And what I've done here is to highlight inred those few days from Februarythe 2nd to the 5th, when David Westerfieldwas on his trip to the desert.So the first expert made this estimatehere, that thebody had been there since the second halfof January.Well, of course this is impossible because,as you know,Danielle was tucked in by her mother onFebruary the 1st.This expert conceded that maybe he couldstretch the dates through intothe first week of February, which includesthe time of Westerfield's desert trip.A second expert, looking at theentomology, put it from the12th to the 23rd of February, basically thesecond half of Februarywhich is time when Westfield was underpolice surveillance.The third expert, a slightly earlier timeframe,but still during that period of policesurveillance.The fourth expert pinned it down to a fewdays,again, it's in middle February.And another expert, again, the late partof February.So, when you see five experts in the samearea giving estimates that are sowidely varying, this does not lend verymuch credibility to the subject.And so the investigators, of course,also consulted medical examiners, and themedicalexaminers gave this estimate here, from thefirst of February to late February.So, as I said at the very beginning, it'svery difficult to give avery accurate estimate, and that's why therange 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 haveto be taken into account.One thing is the weather.This is up in the mountains.The weather in the mountains can be veryvariable.So maybe the weather at the weatherstation, which was some milesaway, was somewhat different from theweather where Danielle's body was left,and therefore it's not possible to make anaccurate estimate.There's also the possibility ofmicro-climates.Anyone who's been in the mountains knowsthat the southfacing side of the mountain, the weatheris quite different,it's distinctly warmer to the north sideof the mountain.And in fact, in mountainous country,you'll only have togo a few hundred metres and you canexperience these changes.Another factor is whether the body wascovered or not.If the body had been covered, then itwould delay when the insects would findit,and this was never really resolved.And then again, of course, there is thepossibility that actuallyDavid Westerfield is innocent and that theentomologists have got it right.Well in the end, David Westerfield wasfound guiltyand he was sentenced to death by lethalinjection,and at the time of recording, he is stillin prison awaiting that sentence to becarried out.So presumably, the jury believed theevidence of themedical examiners and discarded theopinion of the entomologists,and they also considered other evidencesuchas the fingerprints, some blood spots, andthe hair from the van Dam family dog inthe Westerfield RV as indicating guilt.But the story very clearly illustratesthat makingthese estimates can be very, verydifficult indeed.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]
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[MUSIC]An additional technique for bodies thatare in thisstage is to use what is called forensicentomology.Entomology is the study of insects.So, how can we use insects to determinethe time of death?Well, our dead body is lying somewhereoutdoors and it'sstarting to smell and it's detected very,very quickly by insects,and the females, of course, are alwayslooking for a good placeto lay their eggs, and there's nowherebetter than a dead body.They can lay their eggs on the dead body;when theeggs hatch, their children come out, that'sthe maggots, then theirchildren are assured of a really goodsupply of food, sothat they can develop and produce the nextgeneration of blowflies.The life cycles of these creatures areusually fairly regular.So if you can find a maggot off thecorpse, and you can estimatehow old that maggot is, you've got a goodestimate of the time of death.But it has to be done right,because each kind of insect has it's ownlife cycle, with it's own timing.The first thing you have to do is to knowthe species.This is not so easy from a maggot.So, what is typically done is that themaggots are collected from the body, fromthe corpse, they are taken back tothe laboratory and they are reared toadulthood.When you have the adult it is much easierto identify the species.When you identify the species, then ofcourse, you know what the life cycle is.So, when you take your maggot back to thelaboratory and you rear itto adulthood, you also time how long ittakes to reach the adult stage,and then you can back calculate, from thelength ofthe life cycle, how long it had been onthe body.So here, for instance, is the life cycleof the blowfly.It starts out as an egg, the egg hatchesto give a little maggot called the 1stInstar, then it changes to the bigger 2ndInstar, and then the third Instar maggots.And then when they are fed sufficiently,they willturn into a pupa and they will undergotheir metamorphosis,and they will emerge as the adult andthe life cycle of the blowfly has goneround once.Sometimes this technique is very, verypowerful.An example comes from this case, frombackin 1964, involving a man called PeterThomas.In this case, some boys had gone down tothe localwoods because they wanted to collectworms so they could go fishing.And they found more than worms.They found the dead body of Peter Thomasabsolutely covered in maggots.So of course, the police came, and thepolice looked at the body,and they thought that it had been therefor maybe six to eight weeks.But a forensic expert, Professor KeithSimpson, was called in.And Simpson took a look, and he took alook at the maggots,and he disagreed with that six to eightweek estimateand he said, "At least nine or ten days, notmore than 12 days."And when they did the back calculation,that works outas June the 16th or June the 17th of 1964,and these dates proved to be extremelyimportant during the prosecution.Now, the police had identified a suspect inthe case, and this was a man calledWilliamBrittle who had had some financialdealings with PeterThomas, and there was some bad result fromthis.So, it was suspected that Brittle hadmurderedThomas in some kind of dispute over money.So when this went to trial, one of theissues was the time of death.Keith Simpson has said that Thomas wasdead on June the 16th or June 17th.Very importantly, Brittle had no alibi forthat time,but he had a good alibi for dates afterthat.Well, the defense came up with threewitnesses who claimed they hadseen Peter Thomas alive and well on Junethe 20th or 21st,several days after Simpson says he'sdead.So here on one hand, you have themaggots.On the other hand, you have theeyewitnesses.But the defense went a bit too far,they called their own entomologistand they asked their own entomologist totestify based on the maggot evidence.And that's where it went wrong for thedefense, because their expert turned outto agree with Simpson, saying the man wasdead on the 16th or the 17th.Well, who're you going to believe?Are you going to believe the eyewitnesses, orare you going to believe the maggots?Well, in this case, the jury preferredto believe the maggots, not the eyewitnesses.On the other hand, forensic entomology canalso let you down.Let's look at the case here of a younggirlcalled Danielle van Dam who was murderedback in 2002.She was about 7 years old.So, she was last seen alive by her parentson theevening of February the 1st, when hermother put her to bed.The next morning, she was missing.So, from February the 2nd she haddisappeared.Suspicion fell on a man called DavidWesterfield who lived nearby,and he had gone off on a trip into thedesert.This is in California,he'd gone off into the California desertin his RV fora few days, and only came back home onFebruary the 5th.As soon as he came back,he was essentially placed under policesurveillance.So from February the 5th, the police werewatching him, and youreally can't get a better alibi than beingwatched by the police.It took a long time for Danielle's body tobe found.It was finally found on February the 27th,sothis is more than three weeks after herdisappearance.It was up in the California mountains.Obviously by this time badly decomposed,and also, it had been attacked byanimals, maybe coyotes or something.In fact, one of the ways they had touse to identify the body was tofingerprint it.So the fingerprint, even though thetissues were decomposing, theywere able to get a fingerprint off theskin of the finger.Now a key question was, when did Danielledie? When was her body dumped in themountains?Well, here's the calendar of January andFebruary,and they consulted a number of experts,particularly forensicentomologists, to get estimates of whenher body was placed in the mountains.And what I've done here is to highlight inred those few days from Februarythe 2nd to the 5th, when David Westerfieldwas on his trip to the desert.So the first expert made this estimatehere, that thebody had been there since the second halfof January.Well, of course this is impossible because,as you know,Danielle was tucked in by her mother onFebruary the 1st.This expert conceded that maybe he couldstretch the dates through intothe first week of February, which includesthe time of Westerfield's desert trip.A second expert, looking at theentomology, put it from the12th to the 23rd of February, basically thesecond half of Februarywhich is time when Westfield was underpolice surveillance.The third expert, a slightly earlier timeframe,but still during that period of policesurveillance.The fourth expert pinned it down to a fewdays,again, it's in middle February.And another expert, again, the late partof February.So, when you see five experts in the samearea giving estimates that are sowidely varying, this does not lend verymuch credibility to the subject.And so the investigators, of course,also consulted medical examiners, and themedicalexaminers gave this estimate here, from thefirst of February to late February.So, as I said at the very beginning, it'svery difficult to give avery accurate estimate, and that's why therange 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 haveto be taken into account.One thing is the weather.This is up in the mountains.The weather in the mountains can be veryvariable.So maybe the weather at the weatherstation, which was some milesaway, was somewhat different from theweather where Danielle's body was left,and therefore it's not possible to make anaccurate estimate.There's also the possibility ofmicro-climates.Anyone who's been in the mountains knowsthat the southfacing side of the mountain, the weatheris quite different,it's distinctly warmer to the north sideof the mountain.And in fact, in mountainous country,you'll only have togo a few hundred metres and you canexperience these changes.Another factor is whether the body wascovered or not.If the body had been covered, then itwould delay when the insects would findit,and this was never really resolved.And then again, of course, there is thepossibility that actuallyDavid Westerfield is innocent and that theentomologists have got it right.Well in the end, David Westerfield wasfound guiltyand he was sentenced to death by lethalinjection,and at the time of recording, he is stillin prison awaiting that sentence to becarried out.So presumably, the jury believed theevidence of themedical examiners and discarded theopinion of the entomologists,and they also considered other evidencesuchas the fingerprints, some blood spots, andthe hair from the van Dam family dog inthe Westerfield RV as indicating guilt.But the story very clearly illustratesthat makingthese estimates can be very, verydifficult indeed.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]