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[MUSIC]
We wrote this question a few years ago,
this is the Ang Mo Kio case.
It's a completely made-up case and any
resemblance to any real cases is purely coincidental.
So we set the case in Ang Mo Kio.
Ang Mo Kio is a fairly typical Singapore neighbourhood, and I think we chose
Ang Mo Kio largely because it's a fairly typical neighbourhood.
So let's have a look at the information that's been given.
So it's early morning at 4 o'clock, the police enter an apartment.
They find a woman in there who's dead
and you're given some information from the
pathologist, so clearly this woman has been beaten.
You're given some information about the body temperature,
a little bit about the state of Rigor Mortis,
and then we have some information from witnesses, and
some of this information from witnesses concerns the timing
of the different events and finally, there's some DNA evidence.
So we wrote this question particularly
to test three particular areas of knowledge.
We want to test your understanding of time of death
estimation, we want to test your ability to interpret DNA evidence,
and as you'll see later from the diagram of this apartment,
we're interested in seeing what you understand about blood spatter analysis.
So let's look at the questions.
First one, what marks would you expect to find on the attacker?
Well, this is a fight between a man and a woman and from the information
given you know that they've been able
to extract somebody's DNA from underneath her fingernails.
So what you can conclude from that is that in the fight, she must have scratched her
attacker and therefore, what you'd expect to find on the attacker is scratches.
In the information given, you could also see there is a lot of spilled coffee.
So we would also accept an answer such as coffee stains, that's quite logical.
Okay, the apartment has a door.
The door, of course, has a door handle.
So now we're asking the question, what additional
evidence might be found on the door handle?
And this is the answer we'd expect, fingerprints. Because you have
to use your hand to open the door and if you
think about the scene that we've set up in this Ang
Mo Kio case, it would appear to be an unprovoked, unpremeditated attack.
So the attacker wouldn't have made
any precautions to avoid leaving his fingerprints.
There are other possible answers that people might give, but fingerprints is
the one that we were really having in mind at this point.
There was presumably a weapon used to attack this woman but
from the information you're given, there's apparently no weapon in the apartment.
So we're asking the question, where is the likely place to find the weapon?
And this is why, in the diagram of the apartment, you find a broken window.
It's a broken window but the broken glass
is outside the window, not inside in the apartment.
So clearly something has been thrown out through the window.
So perhaps, it was the weapon.
So a likely place to find the weapon is outside the broken window.
You see in the apartment, there is an ashtray.
The ashtray is sitting neatly on the table, there are no
blood stains on the ashtray or on the table under the ashtray.
So if you're thinking that maybe the ashtray was
the weapon, then you're probably thinking in the wrong direction.
If it was the weapon, it wouldn't have been put
neatly back on the table and it would be blood stained.
[BLANK_AUDIO]
Now, question number 4 is not such a direct question as the others.
What parts of the evidence do you consider to be unreliable?
So in order to answer this question, you have to weigh up all of the evidence
presented. And essentially you need to look for what evidence
is inconsistent with the other evidence or even contradicting the other evidence,
and the part of the case where you have
the most items of evidence is in the timing.
So the police were called because of the disturbance
in the apartment and that disturbance happened at 10 p.m.
This is what the neighbours reported.
The next piece of timing evidence we have is about estimation of the time of death.
You're given the body temperature when the body was found.
You're given the normal body temperature. And then we can do
the arithmetic and work out how long the victim has been dead
and if you work out the arithmetic, you will see that
this victim has been dead for between approximately 5 to 7 hours.
That's 5 to 7 hours from the time when the temperature was measured, which is 4 a.m.
So this places the time of death between 9 p.m.
and 11 p.m.,
and that matches nicely with what
the neighbours were saying about this disturbance.
The Rigor Mortis is also consistent with this kind of time frame.
What is inconsistent, is the final witness
saying that the sons of the landlord who have become the suspects,
were seen at Jurong Point at 10:20 p.m.
So Jurong Point is the shopping
centre nearest to Nanyang Technological University,
so we chose Jurong Point for the question because all our students know where it is.
So if the incident happened at 10 p.m.
in Ang Mo Kio, which is on the opposite side of Singapore,
and the suspects were seen at Jurong Point shopping centre at 10:20 p.m.,
then they have 20 minutes to clean up and cross over to Jurong Point.
And when we set up the question, we figured it is not possible to do this.
Looking at the answers from the students when
we use this question in our exam, it seemed
that almost all the students were in agreement that
it's not possible to do this in 20 minutes.
Though there was one student who claimed it was possible
and he knew it was possible because he'd done it,
so we thought about giving his name to the traffic police.
Anyway, we have the disturbance at 10 p.m.
We have the time of death between 9 and 11 p.m.,
so of all the evidence presented, the
part that is probably unreliable is these
last witnesses placing the suspects
at Jurong Point at 10:20 p.m.
Now, how good is an eyewitness?
We've already seen one case in this course where eye witnesses
have been mistaken, and that was in the William Brittle case, in
which the jury preferred to believe the maggots used in the
forensic entomology estimate of the time of death rather than three eyewitnesses.
There's another notorious case, where an eyewitness misidentified
a criminal and this was where a woman misidentified the man who *** her.
He was subsequently imprisoned largely based on her evidence,
but was later cleared and released. And I came across
another case where a person misidentified, and
this is a woman who misidentified her own son.
She was called by the police to come to the morgue to identify a body,
she identified the body as her own son,
it was released, the body was given a proper funeral, and the next day her
son called her. And it turns out that
the body was actually somebody completely different.
So what we are saying is, eye witnesses can be unreliable,
and this is pretty much what Locard was saying in his Exchange Principle.
So the next question is asking you to reconstruct the events in the apartment
in as much detail as you can, and here you have to be careful.
When we say as much detail as you
can, we have to remember we are forensic scientists,
so we can only put in as much detail as is supported by the forensic evidence.
We cannot start thinking about motives and these such
things because usually there's no forensic evidence for them.
So you have to be very aware here of what forensic
science can tell you and don't go beyond that into imagination.
Okay, so when we look at the diagram of
the apartment, we can see the two coffee cups.
So we presume that these two people knew each other and
they were having coffee, which means the first event is that
the murderer was admitted by the victim. And of course, there
is no sign that anyone forcibly broke into the apartment either.
Then, they were presumably having coffee, some
altercation occurred, a fight starts, the cups are dropped, the coffee is spilled
and that's over there by the table.
The first blows are struck along here on the Western Wall of the apartment.
Now when we look at the blood spatter, we can see
that the point of convergence is fairly high off the floor,
so these first blows were struck when the victim was still standing.
There is then a trail of blood across the floor to the
North Wall and presumably, this is the victim trying to get away.
The body is then found on the North Wall.
So that is where the victim must have collapsed.
From the blood spatter on the North Wall, we can conclude that the attack continued
but now you can see the points of
convergence are very low down near the floor.
So this woman must have been beaten by the attacker while
she was on the floor, and that is where she died.
The final question is, who is the prime suspect?
And to answer this question of who is the prime suspect, you need to
use the remaining piece of evidence that we've given you, which is the DNA evidence.
So at the top, you see the DNA extracted from the scrapings
from underneath the victim's fingernail, and then
below that you see the DNA of three of the suspects.
The first one is the landlord, Mr. A.
So if we compare the DNA from underneath the
fingernail with Mr. A, we see something very interesting.
Because we see that in any given STR from the
fingernail scrapings, one matches Mr. A and one does not.
So the simple conclusion from this is that it
cannot be Mr. A because only half of them match.
For it to be Mr. A, all of them would have to be matched.
Second suspect is Mrs. A,
and once again, we see that there is no match, there's only a partial match
so the conclusion is it's not Mrs. A.
However, you can clearly see that the
DNA from underneath the fingernails comes from someone who is a
child of Mr. and Mrs. A, because of the ways the STRs match up.
So it's not Mr. or Mrs. A, but it must be one of their children.
So we have DNA sample given by the oldest son of this couple.
So how does that match up?
So if you compare the top trace, which is from the fingernail scrapings with
the DNA of the older son, you can see quite a lot of it matches.
But to identify the person, it must all match.
It must be a 100% match and you can see as
you work through it that it is not a 100% match.
This attack was, therefore, not carried out by the older son.
Well, if it's not the older son and Mr. A and Mrs. A have only two children,
if it's not the older son, then it must be the other son, the younger son.