3 - 1 - Week 3A - 1 Recent Deaths (10 39), kryminalistyka, introduction to forensic science
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[MUSIC]Let's suppose a body has been found.One of the most importantpieces of information to getis to find out how longthat person has been dead.This is of great importance forreconstruction of the sequence ofevents that led up to the incident.And if this is a murder,then of course, you want tocompare that time of death to the knownmovements of whoever the suspects are.Well, what we're going to do is look atsome of the different techniques thatcan be used.Starting off with bodies that havedied very, very recently.So what happens at death?Well, the first thing ofcourse is the body goes limp.That's because your muscles are undertension when you're alive because yourbrain is telling themto do so.When your brain stops telling yourmuscles to be tense, they go limp,and then all the biochemical machinerythat's going on inside you andis keeping you alivegrinds to a halt.One of the things thatthat machine is doing ismaintaining your body temperature.You are burning fuel that youget from your food in order tomaintain your temperatureat the correct level.That comes to a stop and that meansthat your body will start to cool down.This phenomenon is called Algor Mortis,and is one of the most importantmethods for estimating time of death.However, these estimates should alwaysbe done by someone who is experienced inthis kind of work, because the rate atwhich your body cools can be affectedby all sorts of different factors.One factor is the size of the body.A thin person is going to cool downmuch faster than a fat person,and that is simply a reflection ofthe surface area to volume ratio.The location in which the body is placedis going to make a big difference.If it's out on a hillside withthe wind blowing over it,it's going to be cooling down fasterthan if it's locked in a trunk or a bag.The amount of clothingwill obviously affect it.A naked body or a body wearing justt-shirt and shorts is going tocool faster than one that's buttoned upin a thick, heavy winter overcoat.And of course, the weather will have an effect.If the body is out in cold weatherwith the cold wind blowing and blowing andthe rain falling,it will cool down faster thanon a hot day in the sunshine.In addition to these environmentalfactors, it???s also important tomake sure you measure the correct body temperature.Obviously, the skin will feel coolafter a relatively short time,again depending on environmental factors.But even when we considerinternal organs formeasuring the temperature,we have to get it right.The brain, for instance, it has very littleinsulation from the outside elements,which means that the brain will cool downdistinctly faster than internal organs,and it's those internal organswhich should be measured becausethey will give you the mostrepresentative temperature.And one example would be tomeasure the liver temperature.Well, all things being considered,if we assume it's an average, normal set ofcircumstances, then we can come upwith a general rule that the bodywill cool down at a rate of about 1to 1.5 degrees Fahrenheit per hour.And this will continue untilthe temperature of the body gets down toambient temperature and thenobviously, it will stop cooling down.In fact, it may even start to warm up,because after a few days,the heat generated by the process ofputrefaction may actually causethe temperature to start increasing again.We'll talk about putrefactionin a short time.In addition to Algor Mortis,there's also the very well knownphenomenon of Rigor Mortis.Now, when you die, your brain stopssending signals to your body to do stuff,but that doesn't mean chemicalactivity in your body stops.And the cause of Rigor Mortis isthe continuing chemical action inyour muscles, and it causes themto stiffen soon after death,and then after further time,that stiffening disappears.It's a chemical action within the muscles.It doesn't happen uniformlyover the whole body.It appears first, for instance,in the jaw, spreads to the arms andthen to the legs.So, it will be complete over the bodyin maybe 12 hours??? time andthen it will gradually disappear again.Once again, this needs an experiencedexpert in the field toassess the state of Rigor Mortis inthe body in order to give the estimate.A third method, not sowell known, is Liver Mortis,also known by a number of other terms.Now, Livor Mortis is due to gravity.You consider your blood.Your blood consists of all sorts ofmaterials including the red blood cells,and it's maintained roughly homogeneous andin continuous motion during lifeby the action of the heart.On death, the heart stops, andthen the effects of gravity start tobe felt by the red cells, and they settleout to the lower parts of the body.If, for instance, the body is hanging by the neck,then the red cells will settle intothe legs or the lower parts of the legs,and a distinct discolouration willbe seen down there in the legs.Now, if the body is lying on the ground,it's not quite so simple.Obviously, the red cells willsettle down towards the side ofthe body that is against the ground,under the influence of gravity.You have the body temperature startingout at normal body temperature anddropping gradually to ambient,maybe going up again afterwards.You have the Livor Mortis andRigor Mortis appearing,gradually up to reach their maximum,and then both fading away;and all of these require an estimatefrom an experienced expert.And of course it's a problem.This relies on an expertgiving his opinion,it's not a rigorous scientific method.So a lot of research has been done ontrying to develop more scientific,and hopefully more precise methods.One of the suggestions isto use ocular potassium,and that is the potassium that'spresent inside the eye inthe vitreous humor of the eye.The concentration of potassium in the eyeis lower than the concentration ofpotassium in the rest of the body,and your biochemical machinery makes surethat this concentration differentialis maintained during life.After death, that machinery is no longer operating, sopotassium from the rest of the bodywill gradually diffuse into the eyeand the potassium content ofthe eye will gradually increase.And it's been suggested that this is a goodway of measuring the time ofdeath, relatively free fromenvironmental factors.We can also use circumstantial evidence.Circumstantial evidence typicallywon't give you the time of death, butit gives you a time whenthat person was still alive.For instance, if at autopsy, the stomachand intestine contents are examined,you can get an estimate of the timeof the person's last meal.For instance, the stomachempties in about two hours,so if the stomach is empty,then you know it's at least twohours since that person had a meal.Technology is helping.You can look at someone's watch.Now, normally of course, a watch willnot stop when a person dies, butsuppose this is a drowning caseand it's a cheap watch.In that case, the water will cause the watch to stop andyou'll have a good timing of whenthe person went into the water.Mobile phones are very useful.If you think about it, when was the lasttime you used your mobile phone?Wasn't very long ago, was it?So, in the picture you see Dr. NathanielCary, and this is a quotation from him.He said, "Nowadays, last use of thetelephone can be terribly important." Andhe had been testifying in the trialof a man called Steven Wright,who was convicted of the murder ofseveral women in a short period oftime just before Christmas, 2006.And using the mobile phone records,they were able to estimate time of death.Because when you use your mobile phone,it shows you're still alive,and the time of that phone call isrecorded by the telecoms company, andthis is going to be an increasingly useful method. [ Pobierz całość w formacie PDF ]
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[MUSIC]Let's suppose a body has been found.One of the most importantpieces of information to getis to find out how longthat person has been dead.This is of great importance forreconstruction of the sequence ofevents that led up to the incident.And if this is a murder,then of course, you want tocompare that time of death to the knownmovements of whoever the suspects are.Well, what we're going to do is look atsome of the different techniques thatcan be used.Starting off with bodies that havedied very, very recently.So what happens at death?Well, the first thing ofcourse is the body goes limp.That's because your muscles are undertension when you're alive because yourbrain is telling themto do so.When your brain stops telling yourmuscles to be tense, they go limp,and then all the biochemical machinerythat's going on inside you andis keeping you alivegrinds to a halt.One of the things thatthat machine is doing ismaintaining your body temperature.You are burning fuel that youget from your food in order tomaintain your temperatureat the correct level.That comes to a stop and that meansthat your body will start to cool down.This phenomenon is called Algor Mortis,and is one of the most importantmethods for estimating time of death.However, these estimates should alwaysbe done by someone who is experienced inthis kind of work, because the rate atwhich your body cools can be affectedby all sorts of different factors.One factor is the size of the body.A thin person is going to cool downmuch faster than a fat person,and that is simply a reflection ofthe surface area to volume ratio.The location in which the body is placedis going to make a big difference.If it's out on a hillside withthe wind blowing over it,it's going to be cooling down fasterthan if it's locked in a trunk or a bag.The amount of clothingwill obviously affect it.A naked body or a body wearing justt-shirt and shorts is going tocool faster than one that's buttoned upin a thick, heavy winter overcoat.And of course, the weather will have an effect.If the body is out in cold weatherwith the cold wind blowing and blowing andthe rain falling,it will cool down faster thanon a hot day in the sunshine.In addition to these environmentalfactors, it???s also important tomake sure you measure the correct body temperature.Obviously, the skin will feel coolafter a relatively short time,again depending on environmental factors.But even when we considerinternal organs formeasuring the temperature,we have to get it right.The brain, for instance, it has very littleinsulation from the outside elements,which means that the brain will cool downdistinctly faster than internal organs,and it's those internal organswhich should be measured becausethey will give you the mostrepresentative temperature.And one example would be tomeasure the liver temperature.Well, all things being considered,if we assume it's an average, normal set ofcircumstances, then we can come upwith a general rule that the bodywill cool down at a rate of about 1to 1.5 degrees Fahrenheit per hour.And this will continue untilthe temperature of the body gets down toambient temperature and thenobviously, it will stop cooling down.In fact, it may even start to warm up,because after a few days,the heat generated by the process ofputrefaction may actually causethe temperature to start increasing again.We'll talk about putrefactionin a short time.In addition to Algor Mortis,there's also the very well knownphenomenon of Rigor Mortis.Now, when you die, your brain stopssending signals to your body to do stuff,but that doesn't mean chemicalactivity in your body stops.And the cause of Rigor Mortis isthe continuing chemical action inyour muscles, and it causes themto stiffen soon after death,and then after further time,that stiffening disappears.It's a chemical action within the muscles.It doesn't happen uniformlyover the whole body.It appears first, for instance,in the jaw, spreads to the arms andthen to the legs.So, it will be complete over the bodyin maybe 12 hours??? time andthen it will gradually disappear again.Once again, this needs an experiencedexpert in the field toassess the state of Rigor Mortis inthe body in order to give the estimate.A third method, not sowell known, is Liver Mortis,also known by a number of other terms.Now, Livor Mortis is due to gravity.You consider your blood.Your blood consists of all sorts ofmaterials including the red blood cells,and it's maintained roughly homogeneous andin continuous motion during lifeby the action of the heart.On death, the heart stops, andthen the effects of gravity start tobe felt by the red cells, and they settleout to the lower parts of the body.If, for instance, the body is hanging by the neck,then the red cells will settle intothe legs or the lower parts of the legs,and a distinct discolouration willbe seen down there in the legs.Now, if the body is lying on the ground,it's not quite so simple.Obviously, the red cells willsettle down towards the side ofthe body that is against the ground,under the influence of gravity.You have the body temperature startingout at normal body temperature anddropping gradually to ambient,maybe going up again afterwards.You have the Livor Mortis andRigor Mortis appearing,gradually up to reach their maximum,and then both fading away;and all of these require an estimatefrom an experienced expert.And of course it's a problem.This relies on an expertgiving his opinion,it's not a rigorous scientific method.So a lot of research has been done ontrying to develop more scientific,and hopefully more precise methods.One of the suggestions isto use ocular potassium,and that is the potassium that'spresent inside the eye inthe vitreous humor of the eye.The concentration of potassium in the eyeis lower than the concentration ofpotassium in the rest of the body,and your biochemical machinery makes surethat this concentration differentialis maintained during life.After death, that machinery is no longer operating, sopotassium from the rest of the bodywill gradually diffuse into the eyeand the potassium content ofthe eye will gradually increase.And it's been suggested that this is a goodway of measuring the time ofdeath, relatively free fromenvironmental factors.We can also use circumstantial evidence.Circumstantial evidence typicallywon't give you the time of death, butit gives you a time whenthat person was still alive.For instance, if at autopsy, the stomachand intestine contents are examined,you can get an estimate of the timeof the person's last meal.For instance, the stomachempties in about two hours,so if the stomach is empty,then you know it's at least twohours since that person had a meal.Technology is helping.You can look at someone's watch.Now, normally of course, a watch willnot stop when a person dies, butsuppose this is a drowning caseand it's a cheap watch.In that case, the water will cause the watch to stop andyou'll have a good timing of whenthe person went into the water.Mobile phones are very useful.If you think about it, when was the lasttime you used your mobile phone?Wasn't very long ago, was it?So, in the picture you see Dr. NathanielCary, and this is a quotation from him.He said, "Nowadays, last use of thetelephone can be terribly important." Andhe had been testifying in the trialof a man called Steven Wright,who was convicted of the murder ofseveral women in a short period oftime just before Christmas, 2006.And using the mobile phone records,they were able to estimate time of death.Because when you use your mobile phone,it shows you're still alive,and the time of that phone call isrecorded by the telecoms company, andthis is going to be an increasingly useful method. [ Pobierz całość w formacie PDF ]