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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 raped 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.

