SECTION A

You must answer all the questions in this section. Answer each question on a new page.

Question 1.1

A 24-year old male was arrested for possessing one hundred (100) illicitly made red tablets suspected to contain controlled drug(s). The exhibit was sent to a forensic laboratory for analysis and the report issued was as follows:

The exhibit was found to be one hundred (100) red tablets. The weight of the exhibit was not less than 31.96 grams. A hypergeometric sampling plan was used in the analysis. The analysis shows that at least 90% of the tablets contain ethylene, at a confidence level of 99%.

Ethylone is a Class A Controlled Drug listed in the First Schedule to the Misuse of Drugs Act (CAP. 185).

During the trial, it was found out that for the conclusion to be made, thirty-three (33) tablets were sampled for the hypergeometric sampling. The accused claimed that this was not fair for him, as the other sixty-seven (67) tablets might not even contain any controlled drug. He insisted that all 100 tablets should be sampled for testing and the weight of the pure controlled drug should be given as well.

Based on your understanding of hypergeometric sampling, explain to the accused why it is not necessary:

• to sample all 100 tablets for analysis;
• to quantify the pure weight of the controlled drug.

Question 1.2

• Identify and list three handwriting features that will be examined in forensic document examination.

Question 1.3

Analyze these reported facts:

A 25-year-old male was driving across the Woodlands Checkpoint. Upon checking the back of the car, the custom officer found a small bag of vegetable matter, suspected to be a controlled drug. The driver was asked if he knew what the vegetable matter was. He said it was a Chinese herbal medication for flu. The officer noticed him exhibiting poor balance, drowsy and having a strong smell of alcohol. Being suspicious that the driver might have consumed alcohol and/or drug, the officer sent him to a nearby hospital for clinical investigation. Subsequently, a blood sample was taken for testing blood alcohol. Upon investigation, the subject had a previous record of cannabis consumption. He was referred to the Central Narcotics Bureau for a urine test for controlled drugs.

• Explain what is the common analytical approach in the laboratory in testing controlled drugs in the urine samples.
• The laboratory test shows that the driver’s blood alcohol concentration is not less than 65 milligrams of alcohol in 100 millilitres of blood. Respond, did he commit an offence under the Road Traffic Act? Why?
• The laboratory test on the vegetable matter shows that it contains tetrahydrocannabinol and cannabinol. The urine test shows that monoacetylmorphine is detected. Formulate a view, did he consume the vegetable matter or something else? Explain your answer.

Question 1.4
Analyze these reported facts:

A foreign domestic worker reported that her employer raped her. The victim’s clothing and underwear were collected as evidence.

• Identify and list three practices that will ensure the proper preservation of biological evidence collected.
• List the presumptive and confirmatory tests involved in the context of this case. (2 marks)
• The presumptive test result was positive but the confirmatory test result was inconclusive. Comment on what can be concluded.

Question 1.5

• A bottle of liquid and some fire debris suspected to contain traces of ignitable liquids were found at a fire scene. A jerry can contain some liquid was also found in the car of a man suspected to set the fire at the scene. Discuss how you would determine if the evidence found at the scene is linked to the evidence found in the suspect’s car, including any limitations.

SECTION B

You must answer all the questions in this section.

Analyze the following reported facts:

A woman in her 30s identified as Ms Linda Tay is found dead on her bed in a unit on the fifth-floor at Block 555 in Tampines Ave 15. When the police arrive at the crime scene, they find the deceased’s husband at the scene. He claims he discovered his wife dead after coming back home from work in the evening, and then called the police.

The initial observation indicated that the deceased had sustained a number of stab wounds to her chest, arms and hands. There were also signs of recent sexual intercourse. Under close examination, some blue fibres were found under the fingernails of the deceased. Inside the bedroom, there was a large amount of blood spatter on the bed, the walls and the furniture, including some partial bloody shoeprints on the floor leading to the entrance of the flat. In the living room, there was a broken beer bottle on the floor. The bottle is also stained with blood.

A next-door neighbour informed the police that he had heard loud voices, sounding like an argument between a man and a woman, coming from the unit in the afternoon of that day. The further police investigation shows that Ms Tay had a boyfriend who lives a few blocks away from where she had lived.

Question 2

Based on the facts presented above, express a view and advise on the following queries:

2.1  The on-call forensic pathologist has been called upon by the police to attend the scene. What information from the scene and the body suggests to the forensic pathologist that there may have been foul play?

2.2  The body has been moved to the mortuary for a post-mortem examination. Aside from the post-mortem examination of the body, identify other procedures or tests that may be carried out. Please state reasons.

2.3         The Coroner has decided to hold an inquiry into the death of Ms Tay. Describe the purpose of the inquiry.

Question 3

Based on the facts presented above, comment and advise on the following queries:

3.1  Identify and name the type of trace evidence in this case and where they could be found.

3.2 Explain what the statement “Trace evidence starts at the crime scene” means.

3.3  Discuss the challenges faced in preservation at the scene and analysis of trace evidence in a forensic lab.

Question 4

Applying the facts presented above, advise on the following queries:

4.1  Explain how you would apply DNA profiling to determine who (husband or boyfriend or someone else) had used the weapon (broken bottle or something else) to kill Ms Tay to aid in the reconstruction of events at the crime scene (flat). You can assume that all evidence is available for analyses.

Question 5

5.1 Applying the facts presented above, advise on the following queries:

• What is the difference between ‘positive’ and ‘negative’ impressions?
• Which of these two types would the bloody shoeprints likely be?

5.2   An officer suggested using electrostatic lifting to recover the bloody shoeprints, which you advised against.

• What type of impressions would be better suited for recovery by electrostatic lifting?
• What alternative recovery method would you recommend?
• What is a suitable reagent that could be used, should chemical enhancement be desired?

5.3         An examiner subsequently noted agreement of “general wear” between some of the bloody shoeprints and the test impressions made by a left shoe seized from Ms Tay’s boyfriend.

• What do you understand by the term “general wear”?
• List two factors that could affect the “general wear” of a shoe.

5.4         Only partial shoeprints were recovered at the scene. Could an identification of the shoe(s) that made partial prints still be possible? Why or why not?