3 - 9 - Week 3B - 3 Precipitin Technology (03 54), kryminalistyka, introduction to forensic science
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[MUSIC]So, if you've done your Kastle-Meyertest or your Luminoltest and you've determined that a stainfound at thecrime scene really is blood, there's stillthe question ofwhether it's human blood or whether itbelongs to some animal.Now, we can use antibody technology todetermine which species blood comes from.The way this is done is that a sample ofhuman blood is injected into a rabbit.The rabbit's immune system reacts to thepresence of the humanblood and it produces antibodies againstthose components in the human blood,so serum from that rabbit's blood canthen be used as the test reagent.For instance, if we take our suspectedhumanblood and treat it with the rabbit serum,then when the human blood meets therabbit serum that contains the antibodies,then the antibodies, of course, will bindto components in the human blood,and there will be a distinctive sign thatthere is an interaction.If the two interact, then it proves thesample is from human blood.This is usually done in a gel.So, the antigen and the antibody areplaced in separate wells in a gel.And then, using an electric field,they are induced to migrate towards eachother.If there is an interaction between theantibody and the sample when thetwo meet, then there will be a visibleprecipitin line in the gel.If there's no interaction, then there isno visible line,and you'd know that it's not human bloodafter all.This kind of technology is important.It has been used.For instance, some years ago, this man,ChristopherNudds, was accused of killing his friend,Fred Moss.Part of the evidence for this accusationwas the presence of many bloodstainsin Christopher Nudds' Range Rover, but itturned out that Nudds was a hunter.So, the bloodstains presumably were fromsome of the birds and animals thathe had captured and killed and drivenback home in his Range Rover.So the precipitin test had to be used tofindout from which species all of these bloodstains came from.And sure enough, most of the bloodstainsin the Range Rover were from hunting.They came from birds and animals such asrabbits.However, that was most of the bloodstains,it wasn't all of the bloodstains.Some of the bloodstains indeed, turned outto be human.Once the human bloodstains had beenidentified, then it waspossible to use DNA to find out whoseblood it was,and it turned out that human blood in theRange Rover matched Fred Moss.Christopher Nudds was subsequentlyconvicted of this murder,and it's going to be a long time before hegoes hunting again.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]
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[MUSIC]So, if you've done your Kastle-Meyertest or your Luminoltest and you've determined that a stainfound at thecrime scene really is blood, there's stillthe question ofwhether it's human blood or whether itbelongs to some animal.Now, we can use antibody technology todetermine which species blood comes from.The way this is done is that a sample ofhuman blood is injected into a rabbit.The rabbit's immune system reacts to thepresence of the humanblood and it produces antibodies againstthose components in the human blood,so serum from that rabbit's blood canthen be used as the test reagent.For instance, if we take our suspectedhumanblood and treat it with the rabbit serum,then when the human blood meets therabbit serum that contains the antibodies,then the antibodies, of course, will bindto components in the human blood,and there will be a distinctive sign thatthere is an interaction.If the two interact, then it proves thesample is from human blood.This is usually done in a gel.So, the antigen and the antibody areplaced in separate wells in a gel.And then, using an electric field,they are induced to migrate towards eachother.If there is an interaction between theantibody and the sample when thetwo meet, then there will be a visibleprecipitin line in the gel.If there's no interaction, then there isno visible line,and you'd know that it's not human bloodafter all.This kind of technology is important.It has been used.For instance, some years ago, this man,ChristopherNudds, was accused of killing his friend,Fred Moss.Part of the evidence for this accusationwas the presence of many bloodstainsin Christopher Nudds' Range Rover, but itturned out that Nudds was a hunter.So, the bloodstains presumably were fromsome of the birds and animals thathe had captured and killed and drivenback home in his Range Rover.So the precipitin test had to be used tofindout from which species all of these bloodstains came from.And sure enough, most of the bloodstainsin the Range Rover were from hunting.They came from birds and animals such asrabbits.However, that was most of the bloodstains,it wasn't all of the bloodstains.Some of the bloodstains indeed, turned outto be human.Once the human bloodstains had beenidentified, then it waspossible to use DNA to find out whoseblood it was,and it turned out that human blood in theRange Rover matched Fred Moss.Christopher Nudds was subsequentlyconvicted of this murder,and it's going to be a long time before hegoes hunting again.[BLANK_AUDIO] [ Pobierz całość w formacie PDF ]