AY2020 Semester 1
G101 Critical Thinking and Problem Solving
Lesson 06: What does the evidence say?
Worksheet (Facilitator)
*The Omnivirt 360o murder scene may not work on CHROME. Try on IE.
1. Suppose A claims that B had stolen her wallet on Monday. Comment on whether you
would accept each of the following information as evidence of B having stolen A’s wallet.
Try to identify possible problems with each.
No. Information
i
Video showing B taking A’s wallet
from her bag when she was not
looking
ii
Photo of B with her hands inside
A’s bag
iii
C claiming that he saw B stealing
A’s wallet on Monday
iv
B confessing to stealing A’s wallet
when questioned by their lecturer.
v
A saying that in an argument with
B, B had told her to “watch out for
her money”
Comments
Yes. There is a video proof(direct evidence)
that is a credible source showing that B did
steal A’s wallet particularly when she was not
looking.
Yes. A photo evidence (direct evidence)
proves that B was trying to steal something
from A’s bag.
Yes. C is a third witness(direct evidence)
who saw B stealing A’s wallet. This aids in
the suspicions against B thus supporting the
truth of the claim
Yes. Upon confrontation with the lecturer she
was complied to tell the truth by admitting her
crime. (Direct evidence)
Yes. B threatens A to ‘watch out for her
money’ in a vindictive way during the
argument, however it does not entirely prove
her intentions was to steal it afterwards.
More inferences are needed. (Circumstantial
evidence)
2. Evidence can be grouped into two types – direct and circumstantial.
Direct evidence supports the truth of a claim directly, without need for any additional
inference*. For example, W claims that X was smoking at the carpark at 9.15am. A
CCTV footage of X smoking at the carpark at 9.15am would be considered as direct
evidence as no further inference is required.
Circumstantial evidence, on the other hand, does not support a claim directly.
Circumstantial evidence requires an inference* to support the truth of a claim. On its
own, circumstantial evidence allows for more than one explanation. For example, W
claims that X was smoking at the carpark at 9.15am. The testimony from Y that he
saw X buying a pack of cigarettes at a shop at 9am that morning would be
considered ‘circumstantial evidence’, as we need to reason that since X bought a
pack of cigarettes, he intended to smoke that morning. However, this is not direct
evidence since X could be buying that pack of cigarettes for his friend.
*Inference can be defined as a mental process which we reach a conclusion based on specific evidence.
Before evaluating any evidence, we should first identify what is the claim.
a. Consider the claim ‘Ken shot Jason with a gun’. Identify which information is direct
evidence and which is circumstantial evidence. Explain your answers.
No.
1
Information
You see Ken walk into Jason’s
house through the front door. One
minute later, you hear a gunshot
sound. Then you see Ken walk out
of the house.
Type of Evidence
Direct /
Circumstantial
2
You are in Jason’s house. You see
Ken walk in with a gun. You see Ken
shooting Jason with the gun.
Direct /
Circumstantial
Explanation
There is no
substantial
evidence to prove
that ken shot
Jason solely for
the fact that he
was present in the
crime scene. More
inferences are
needed to support
the truth of the
claim.
There is
substantial
evidence to prove
that ken shot
Jason because I
was an eye witness
for the crime
committed. Hence,
my testimony is a
direct evidence to
support the truth
of the claim.
Therefore, no other
inferences are
needed.
b. Now go back to Question 1 and try to identify the direct evidence and circumstantial
evidence for the claim.
3. When we examine different pieces of evidence, we may find that some of them
corroborate and some may contradict one another.
Evidence that corroborates is evidence that tends to support a claim that is already
supported by some initial evidence, therefore confirming the claim. For example, W, a
witness, testifies that she saw X smoking at the carpark at 9.15am. Meanwhile, Y,
another witness, testifies that when he interacted with X at 9.30am, he detected the smell
of cigarette on X.
Evidence that contradicts is evidence that tends to refute a claim that is already
supported by some initial evidence, therefore confirming the claim. For example, W, a
witness, testifies that she saw X smoking at the carpark at 9.15am. Meanwhile, Y,
another witness, testifies that he saw X doing push-ups at the carpark at 9.15am.
Before evaluating any evidence, we should first identify what is the claim.
a. Consider the same claim ‘Ken shot Jason’.
To support the claim, a witness tells you this: I saw Ken walk into Jason’s house
through the front door at 8.30am. One minute later, I heard a gunshot sound. Then I
saw Ken walk out of the house at 8.35am.
Which of the following pieces of information will corroborate the witness’s testimony?
Which will contradict? Explain your answers.
1. Jason was found dead on the 3rd floor. It takes 3 minutes for an average adult male
to run up to the 3rd floor.
Contradict. The witness heard the gunshot one minute after ken walked into the
house therefore, ken would not have had enough time to go to the third floor and
pull the trigger on Jason. Thus, does not support the claim that “ken shot Jason”.
2. Jason was found dead on the 1st floor living room, accessed immediately after
opening the front door.
Corroborate. The witness heard the gunshot one minute after ken walked into the
house through the front door therefore, ken took a minute to shoot him since Jason
was at the 1st floor that is immediately accessible by opening the front door. Thus,
the timing Ken entered the house and the gun shot heard was relatable hence it
does support the claim that “ken shot Jason”.
3. A neighbour said she heard a gunshot around 8.30-8.35am that day.
Corroborate. The timing around ( 8.30-8.35am) when the neighbour heard the
gunshot was the same time ken entered and left Jason’s house. Therefore, it
implies that Jason was present at the crime scene and does support the claim that
“ken shot Jason”.
4. A friend, John said he was drinking coffee with Ken at a café from 8-9am on that
very same day.
Contradict. John testified that Ken was with him at the café during the time Ken
was shot hence, less likely ken shot Jason if he was not present at the crime scene.
Therefore, it does not support the claim that “ken shot Jason”.
Evidence that corroborates
Evidence from 2 and 3
Evidence that contradicts
Evidence from 1 and 4
4. Apply the concepts to the problem statement
a. Look at the items in the crime scene photo. Comment on how you will make sense of
each of them.
https://www.omnivirt.com/c/33947
No. Item and accompanying information
Comments
1
Used tissue
 No blood trace found
 DNA tests do not trace
it to the victim, her
daughter and the two
known suspects
(Adrian Lee and
Jackson Tan)
This may belong to a neighbour as
used tissues are commonly found
at lift lobbies. Unless there is a 4th
suspect (or accomplice).
2
Empty cardboard box
with pocket knife on top
 Fingerprint tests on the
box and pocket knife
do not trace it to the
victim, her daughter
and the two known
suspects (Adrian Lee
and Jackson Tan)
3
1.5 litre coke bottle that
is empty
 Saliva and fingerprint
tests conducted do not
trace it to the victim,
her daughter and the
two known suspects
(Adrian Lee and
Jackson Tan)
4
Torn half of The Straits
Times dated 9 April 2019
(Tuesday)
 Fingerprint tests
conducted do not trace
it to the victim, her
daughter and the two
known suspects
(Adrian Lee and
Jackson Tan)
 There was one set of
fingerprints found that
is unknown
The pocket knife on top of the
empty cardboard could have been
Jackson Tan’s ( ex boyfriend’s
)since he had a pocket knife
collection at home. However, no
traces of his or the victim’s
fingerprints were found. Thus, it
either could have been just items
originally there before the crime or
the robber’s( third suspect)
The 1.5litre empty coke bottle
found could have been Jackson
Tan’s since he has 10 others
stocked up in his house storeroom.
However, no traces of his or the
victim’s salvia and fingerprints were
found. Thus, it either could have
been just an item originally there
before the crime or the robber’s(
third suspect)
The torn half of the Straits Times
dated 9 april 2019 could have been
Adrian Lee’s since he has a
collection of newspapers at home
and particularly the same
newspaper(9 april 2019) found at
the crime scene with the front page
missing. However, no traces of his
or the victim’s fingerprints were
found but one unknown fingerprint.
It either could have been a regular
person’s newspaper who is not
related to the murder or the
robber’s( third suspect).
5
Footprint (right foot)
Size: US 9
6
A pair of partial footprints
This could be the murder’s footprint
who has a foot size US 9. Adrian
Tan shoe size is 8 while Jackson
Tan’s is 9. Thus, higher suspicions
that Jackson could have been
present at the crime scene and
committed the murder or the
robber’s shoe size is 9 and he
committed the murder or a regular
trespasser’s before the murder.
This could have been jackson’s
footprint or the robber or just a
regular trespasser’s before the
murder was committed.
7
A pair of footprints
Size: US 9
This could have been the same
footprints from Jackson or the
robber’s or just a regular
trespasser’s before the murder
was committed.
8
Blood drips on the floor
This is probably the blood drips
from the victim’s body when she
was stabbed.
9
Blood pool on the floor
This is probably the blood from the
victim’s body when she was
stabbed and her body lying on the
floor with blood oozing out.
10
Blood splatter pattern on
recycle bin
This is probably the blood splatter
from the murder slashing the
victim’s neck.
11
Blood splatter pattern on
dustbin
This is probably the blood splatter
from the murder slashing the
victim’s neck.
12
7 stabs found on victim’s
chest
7 stabs suggest that it is rather a
vengeance than robbery. Adrian
and Jackson are more suspicious.
.
Fingerprints on shirt
traced back to the victim
only
13
One stab found on
victim’s back
Victim was first stabbed on the
back unexpectedly.
14
One deep gash across
victim’s neck
There were intentions to murder
her brutally not only rob her.
b. Based on the evidences collected, are there any direct evidence to indicate who might
have murdered Mrs Linda Lee? How does the presence/absence of direct evidence
affect the way you arrive at your conclusion?
No, there are no direct evidence. All the evidences found are circumstantial evidences
that does not support the claim directly. The absence of direct evidence makes it more
difficult to find the murderer because more inferences are needed to be gathered and
investigated to arrive at the conclusion. Compared to the presence of direct evidence,
it will be easier as there is substantial evidence to support the claim and arrest the
murderer.
c. Consider the evidence at the crime scene, the three interview transcripts (attached
below) and the information at Mr Adrian Lee and Mr Jackson Tan’s houses (attached
below). What are some evidence that corroborates who the prime suspect is? What
are some evidence contradicts who the prime suspect is?
Interview-Jenny Lee Interview-Adrian Lee
Interview-Jackson
Tan
Items in Adrian and
Jackson houses