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.
Week 1 - 8 Forensic Laboratories
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En provenance du cours de Nanyang Technological University, Singapore
Introduction to Forensic Science
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À partir de la leçon
Introduction to Forensic Science
Rencontrer les enseignants
Roderick BatesAssociate Professor
Division of Chemistry & Biological Chemistry | School of Physical & Mathematical Sciences
[MUSIC]
In the first part of the 20th century, police forces around the world
started to set up their own specialized forensic laboratories.
So one of the first, of course, was in Lyon, set
up by Locard himself. And then other countries in Europe followed suit,
and also in the United States, laboratories started to be set up.
So by 1932, the F.B.I. had set up a national laboratory in the
United States, and a few years later, Scotland Yard's lab was set up.
Singapore's facilities were set up much later.
Chao Tzee Cheng, who we have already mentioned,
started his work in the 1960's, but even
as early as 1929, there was a chemical
analysis service available to the Straits Settlements Police.
Nowadays, Singapore's facilities are all part of the Health Sciences Authority.
So I think we have already realized that
Forensic Science is a very, very diverse subject.
So a forensic science laboratory would contain within it many
different units to handle all sorts of different kinds of science.
Now in this section, we'll talk about some of those
different units that might be in a forensic science laboratory,
and while some of them are clearly essential for any
forensic science lab, others would only exist in the more specialized
or more extensive laboratories, and a few might be separate
skills which would not be in a forensic science lab itself.
So a forensic science lab would be likely
to have some kind of physical science unit, and
such a unit would handle a lot of
chemical and physical analyses including chemical tests, spectroscopy, microscopy.
It might deal with drugs. It might deal
with material fragments such as glass and paint.
It might deal with explosives, soil and so on, a collection of miscellaneous items.
A biology unit might also exist.
Forensic scientists often have to analyze biological samples such
as hair, or for instance, botanical samples such as plants.
One facility, one capability that is essential is DNA.
A forensic science laboratory nowadays has to have access to DNA analysis services,
and we are going to have a separate lecture on that topic.
A firearms unit might be important as well.
How important, of course, depends on which country you're in.
And this unit would deal with guns, would deal
with bullets, would deal with cartridge cases, and so forth.
Documents. Some forensic science laboratories have
a specialized group to look at documents to determine whether documents have been
faked or forged, and these might have experts who specialize in the
analysis of handwriting, print, paper, ink, etc.
Another specialized unit that some places will have is a photography unit.
Not only is photography important for recording
evidence and then presenting the evidence, there
are also specialists who can analyze photographs
to see whether they are genuine photographs.
If you take a look at this photograph, it shows the late leader of North Korea.
And there was a time when he disappeared from public view,
and there was much speculation in the West that he was ill.
To attempt to dampen down the speculation, the North Koreans issued this photograph.
But if you look at it carefully, you notice a few oddities about it.
For instance, on the left and the right of the photograph, you can see a black line
running along the wall, but that black line does not run behind Mr. Kim.
You can also see that this photograph was taken when the sun was at a low
angle, either early morning or late afternoon, and
you can see the shadow of the soldiers' legs.
But curiously, the shadow of Mr. Kim's legs is
at a quite different angle to the other shadows.
These are things that a photographer could see just by inspection, but a more careful
analysis reveals that the pixels that make up the photograph don't match.
So the pixels near to Mr. Kim's ankles don't
match the pixels on the wall just next to it.
So the conclusion is that this photograph is not a genuine photograph.
It's been photo-shopped.
Here is another photograph which caused a
great deal of controversy over many, many decades.
This is the so-called "Surgeon's" photograph taken in 1934 on the Bank of Loch Ness
in Scotland, and it purports to show the Loch Ness Monster swimming in the lake.
Analysis of this photograph couldn't reach a conclusion.
It turns out that the photograph is absolutely genuine,
there was no tampering with the photograph.
In this case, it's the monster that's a fake.
It was a model monster, and somebody just put it in the lake and photographed it.
It took many years for it to be exposed as
a hoax, and that's because the man who did the
hoax didn't confess to it until he was on his
death bed, which turned out to be 60 years later.
Toxicology is another important capability to have
access to, and this involves the analysis of body fluids.
For instance, if someone is found dead on their bed and there's
an empty bottle of sleeping pills next to them, then of course,
you're going to analyze the blood or body fluids of that person to
see if there's a high concentration of whatever drug is in their system.
And fingerprinting is very important.
So, the police or the forensic science laboratory have
to have access to technology, not only the expertise
to look at fingerprints, but also the technology to
make fingerprints visible, as not all fingerprints are immediately visible.
And this will be the subject of another lecture.
On TV shows, you often see the polygraph or the lie
detector, and some laboratories or police forces will also have this facility.
And so it raises the interesting question of, "Can we detect a lie using science?"
Well, you can try, but generally, most
jurisdictions do not accept polygraph results as evidence.
A very specialized form of forensic science is voiceprint analysis.
If the only thing you have that is purports to come from someone is the
sound of their voice, can you prove that that voice actually came from that person?
So when Osama bin Laden was still alive, occasionally audio recordings,
reportedly of him, would start to circulate and agencies such as the C.I.A.
would do a voiceprint analysis to see if they really were from bin Laden.
This technology was also used in the 1970's
concerning the eccentric, reclusive millionaire or billionaire, Howard Hughes.
In 1971, an author called Clifford Irving was claiming
that he had a manuscript which was the authorized biography of Howard Hughes,
and he was paid a very large sum of money by
one of the big publishers for the rights to this authorized biography.
Well, when Mr. Hughes heard about this, he was clearly quite upset because he hadn't
authorized any biographies, and he denied that this was the authorized biography.
To make his denial, he organized a teleconference,
and he had to do it by a teleconference,
he was an extreme recluse.
He never appeared in public, and at the time,
he was staying in a luxury penthouse in the Bahamas.
So the assembled journalists would listen to his
voice over the telephone line coming from the Bahamas,
but how do you prove that it really is Howard Hughes' voice?
Well, of course this was done by voiceprint analysis.
When the recording of Hughes at the
teleconference was compared to a recording of
him speaking many years before, it was confirmed that it really was his voice.
And consequently, the author of the so-called
authorized biography was subsequently convicted for fraud.
[BLANK_AUDIO]
Another technique sometimes used by police forces
is psychiatric profiling, and this is trying
to tell something about the criminal from the way that the crime has been committed.
This probably wouldn't be a facility in a forensic science laboratory,
an expert psychiatrist would be called into the case, and we'll
have a little discussion of this in one of the later lectures.
Computer forensics is becoming increasingly important.
A large part of computer forensics is
retrieving data that has been deleted from computers.
In addition, as data is transmitted round the world electronically, it's
also following that electronic trail to find out where people have gone.
Now forensic engineering, this is not a subject
that a forensic science laboratory would likely have.
This would be done by a professional engineer
who was qualified or experienced in this area.
So what is forensic engineering?
Well, for example, in the picture you can see the I-35 bridge in
Minneapolis, Minnesota, which collapsed in August 2007.
So, forensic engineers were called in to determine why the bridge collapsed.
The initial theory that went round in this case
was that it was due to the corrosive effect of
pigeon droppings, but it was later concluded that it was
actually a design fault when the bridge was originally built.
Forensic entomology. Entomology is the study of insects, and forensic entomology
is where you use the insect population of the crime scene to gain some information,
and again, we'll talk about this subject in a later lecture.
Forensic geology, this is soil analysis.
We'll have one example in a later lecture.
Curiously, forensic geology is something that is much more
common in Sherlock Holmes stories than in real forensic science.
Now, forensic anthropology is quite an important topic,
and this concerns the analysis of skeletal remains.
So if a skeleton is found, it has to be identified,
and it's usually the job of a forensic anthropologist to do this.
Skeletal remains do appear if somebody dies in a place where nobody ever goes to,
then the body can decompose, and by the time
it's finally found, all that remains is a skeleton.
For instance, in 2011, a bank
in Abbeville, Louisiana, was doing some serious renovations to their building,
and they had an old building and it included a proper old-fashioned chimney.
And when they knocked open the chimney, they found a human skeleton,
and this was subsequently identified as being the skeleton of this man, Joseph
Schexnider, who disappeared more than a quarter of a century before, in 1984.
So in this case, the forensic anthropologists were
able to identify who the skeleton belonged to, but
of course any evidence about how he died
or why he was in the chimney had disappeared.
Now, one of the techniques that a
forensic anthropologist will use is called facial reconstruction.
What they do is to take the skull and then rebuild the flesh on the skull
so that you can see what that person looked like when they were alive.
Sometimes this technique is remarkably successful.
So here for instance, on the left you can see
the reconstruction, on the right you can see the real person.
In this case, the skeleton was found rolled up in a carpet
and the forensic anthropologist also had the bonus that the hair
was preserved, which can make a big difference to the appearance.
So after the face was reconstructed, the image was shown on a
TV program, and people called in and said they recognized the person.
And once the police had the name of the victim,
they could then start the investigation into what had happened,
and in this case, it lead to the conviction of the murderer.
It's not always so easy.
In this second case here, on the left you can see the person, and he was killed in
a terrible underground fire at King's Cross station in London in 1987.
The reconstructed face is on the right.
And it took more than 15 years before
family members came forward and made the identification.
In this case, it's possibly because the man was much older than had been expected,
and it's very difficult to tell about age accurately from skeletal remains.
Now, both these cases I've shown here,
the facial reconstruction is done using modelling clay.
And nowadays, of course, it can be done
by computer and it can be done electronically.
Odontology is surprisingly important.
Odontology is the study of teeth.
Many times, teeth can be used to identify people by comparing the
teeth in the head or the skull with whatever dental records are available.
Sometimes, odontology comes in with other uses.
This is Ted Bundy,
he was one of the most famous serial killers in the
United States of America, and he
specialized in young female college students.
Now Bundy was a pretty clever guy.
He was actually a law student himself,
and he was very careful to make sure that he never left any evidence behind.
But he made a mistake in one case, and he actually
bit one of his victims, leaving his teeth marks in the body.
So, with an order from a judge, the police were able to force
Bundy to give a teeth impression, and when that was compared to the
bite mark in the body it proved that Bundy had been the murderer,
and Ted Bundy was executed in January 1989.
Now, teeth don't have to be real teeth, they can also be false teeth.
This is the story of J.G. Haigh, nicknamed Acid Bath Haigh,
who was finally convicted of his crimes back in 1949.
It's believed that he killed nine people, but the person who
led to his capture was an elderly lady called Olive Durand-Deacon.
Now, Haigh lived in a hotel in London,
but he also had a shed out
in the countryside, and he lured Mrs. Durand-Deacon
to his place in the countryside with some
talk of investments in business of some kind.
Now, Haigh was a fairly clever man, but not a very clever man, and he'd heard this
concept that it's not possible to have a conviction for a crime without a body.
Unfortunately, he'd misunderstood the concept.
The concept is that there must be the body
of evidence to prove that a crime had occurred,
but Haigh took it very literally and thought that it had to be a real
body, and if there was no real body then there could be no murder charge.
So what Haigh very carefully did was to make sure he destroyed the bodies
of all his victims, and he did
this by dissolving them in concentrated sulfuric acid.
So he would put the body in a drum with conc. sulfuric acid for several days,
come back later when the body had dissolved,
and simply pour the whole mess down the drain.
Well, when Mrs. Durand-Deacon had disappeared, and the
police were called, they went to Haigh's place
to investigate, and they found two items that
proved to them that Mrs. Durand-Deacon had been murdered.
One was a gall-stone, and the other one was her false teeth.
Both of these items are quite difficult to dissolve in sulfuric acid.
Of course, false teeth are highly
individualized, so simply taking the false teeth
to Mrs. Durand-Deacon's dentist they could identify them and prove that it was her.
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