Week 3A - 2 Decomposing Bodies I (Putrefaction)

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Del curso dictado por Nanyang Technological University, Singapore

Introduction to Forensic Science

458 calificaciones

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Nanyang Technological University, Singapore

Introduction to Forensic Science

458 calificaciones

We have all seen forensic scientists in TV shows, but how do they really work? What is the science behind their work? The course aims to explain the scientific principles and techniques behind the work of forensic scientists and will be illustrated with numerous case studies from Singapore and around the world. Some questions which we will attempt to address include: How did forensics come about? What is the role of forensics in police work? Can these methods be used in non-criminal areas? Blood. What is it? How can traces of blood be found and used in evidence? Is DNA chemistry really so powerful? What happens (biologically and chemically) if someone tries to poison me? What happens if I try to poison myself? How can we tell how long someone has been dead? What if they have been dead for a really long time? Can a little piece of a carpet fluff, or a single hair, convict someone? Was Emperor Napoleon murdered by the perfidious British, or killed by his wallpaper? *For Nanyang Technological University (NTU) students, please be noted that this course will no longer be eligible for credit transfer.

De la lección

Time of Death; Blood

Week 3A - 1 Recent Deaths10:39

Week 3A - 2 Decomposing Bodies I (Putrefaction)6:13

Week 3A - 3 Decomposing Bodies II (Forensic Entomology)11:50

Week 3A - 4 Analysis of Skeletal Remains I8:29

Week 3A - 5 Analysis of Skeletal Remains II11:37

Week 3A - 6 Ötzi Case; Summary3:36

Week 3B - 1 Blood13:02

Week 3B - 2 Tests for Blood6:54

Week 3B - 3 Precipitin Technology3:53

Week 3B - 4 Blood Spatter Analysis8:17

Week 3B - 5 Lord Lucan Case; Summary7:04

Conoce a los instructores

Roderick Bates
Associate Professor
Division of Chemistry & Biological Chemistry | School of Physical & Mathematical Sciences

[MUSIC]

So what do we do if the body that we found has been there for several days, and

it's already cooled down to ambient temperature, and the

Livor Mortis and the Rigor Mortis have both passed?

Well, probably what we would have to do at this stage

is to look at the state of putrefaction of the body,

and once again, this needs an experienced person

to make a judgment and give his opinion.

So what is putrefaction and how does it happen?

Well, when you're dead, of course, you're dead, but all the microorganisms

that live inside you, they're not dead, and they keep on going

and they will start to eat you.

Essentially they will take your tissues and they will

break them down chemically and use them as nutrition.

But as a by-product, they will produce all

sorts of chemicals, including gases and volatile chemicals,

and it's these chemicals produced by putrefaction that

give an abandoned dead body its particular smell.

And if you've ever walked past a ditch where

there's a dead dog, you know what I mean.

So, an experienced examiner can look at the body and make a judgment.

Of course, he does have to take into

effect all sorts of environmental factors, particularly temperature.

If it's a very hot place, rather than a very cold place,

then of course, there's going to be a big difference in the rates.

You also get effects due to drug use, because

if someone has been a heavy drug user, the

presence of all those drugs in their body can

affect the rate of which the microorganisms do their stuff.

And again, this relies on experience.

So, one of the problems is there's not many hard

scientific studies on the rate of decomposition of human bodies.

So, some studies are ongoing.

One of them is, as you see, at the University

of Tennessee, Knoxville, where they have a so-called "Body Farm",

which is an area of open ground which they fenced

off, and they will place donated bodies in particular situations -

clothed or unclothed, partially buried, etc. -

and then they can scientifically observe the process of putrefaction,

and maybe this will make estimates more scientifically reliable.

Well, during putrefaction, this is roughly what happens.

After a few days, the body will start to discolour and also it will start to swell.

The reason for the swelling is the gases produced by

the putrefaction process are inflating the body slowly, like a balloon.

As the days go past, the staining spreads and the veins of

the body start to become discoloured as the materials in your blood decompose.

Further days pass, the abdomen swells even more

as more gas is developed by the putrefaction process.

The skin starts to blister, and eventually the abdomen will

become very tight and swollen because of all the gas inside.

The tissues also break down, so the tissues

lose their structural integrity, and they start to soften.

And that means that the organs and cavities inside the body, which have

been filled with these putrefaction gases,

then burst, a little bit like balloons.

In addition, the fingernails will no longer be

attached to the fingers and they will fall off.

So in a typical case, maybe in four

weeks, the soft tissues will be starting to liquefy,

and one of the consequences of this

is that the face is no longer recognizable.

So if the body is found at this stage, somebody just looking at it

can't tell who it is, and it will have to be identified by other means.

So, a body exposed to the elements will ultimately turn into a skeleton.

How long this takes is very dependent on environmental factors, so

some people in some places might say it takes several years.

Here in hot, tropical Singapore, it can take

as little as two weeks for that to occur.

Now, not all bodies putrefy.

If the environmental conditions are right,

particularly if the conditions are extremely dry,

then the body will become mummified and the tissues will actually be preserved.

So mummification does happen by accident because

the body happens to be in those circumstances.

But of course, the most famous kinds of

mummification is where it has been done deliberately.

So these four gentlemen in the slide here were all mummified.

There's Pharaoh Ramses the Second of Egypt.

This is Lenin, the founder of Communist Russia,

who was mummified and preserved by having a

secret chemical injected into him after his death,

and his body is still there in Moscow.

If the Russians did it, then of course the Chinese did it.

So there's Chairman Mao.

And the last of these four

gentlemen actually specifically wished to be mummified,

and he said so.

And he is Jeremy Bentham,

the English philosopher who was also the

founder of University College London, and if you

go to University College London, you can go and see him there, he's still there.

[BLANK-AUDIO]

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