Arson Detection

Accelerants like ignitable liquids in many arson cases are used to start or speed up a fire. As a result, the key step in the detection of ignitable liquid residue in the investigation is the fire scene. In the cases where arson is suspected, the identicalness of identified accelerant is important information to the investigation. For instance, the ignitable liquids like gasoline and diesel which are petroleum-based products are frequently used since they are very accessible and easy to ignite. However, to understand the type of ignitable liquid used, fire debris is analyzed. The fire debris analysis is very important as it gives insight to what really started the fire. Therefore, to determine the fire debris in the accelerant, the gas chromatography is used to analyze the evidence. Apart from using gas chromatography for successful analysis of the evidence, the analyst should make sure the ignitable liquid is in volatile form.

In addition, the accuracy of the laboratory analysis will depend on various factors such as sample collection, sample preservation and the quality of the sample. Nevertheless, it is very significant for sample material to be located in the shortest time into an appropriate container. The reason for using an appropriate container is to stop the contamination of the sample and to give a safer mean of transporting and preserving of the evidence. Sampling containers like glass canning jar, fire debris, and metal tin are highly preferred for fire debris.

Primarily, the packaging of the sample it will depend on its state. For instance, if the samples are in a solid state then a sampling container should packed two-thirds of its volume. Moreover, the packed sample should be able to permit volatiles migration in the headspace. Besides volatile migration, the large solid sample should be broken down into smaller pieces to increase the surface area of extracted solid. In fact, the efficiency of packaging solid samples lies with some conditions. For instance, dilution of a sample by adding suspected material that contains ignitable liquid is discouraged, refrigeration soil sample that contains suspected ignitable liquid is encouraged and lastly as to mention few, a sample should be put in a container adjacent to its size.

Furthermore, if the sample is in a liquid state then using of syringe or pipette is used to collect the alleged liquid into a vial glass. Additionally, unused cotton is used to remove the suspected liquid residue of the surface of sampling and also it must accede as a control sample. 

Drug Analysis

According to the Misuse of Drug Act (cap 185), the consumption of controlled drugs can be proved by records and returns making from medical practitioners, pharmacists, dentists, or people who distribute controlled drugs.

According to the Road Traffic Act (chapter 276), a person who is under the drug influence is unfit to drive or attempt driving vehicle in public places. Therefore, blood alone has a small chance of proving the level of intoxication unless it is interpreted with the case-specific factors and reviewed holistically with appropriate toxicological data.

Urine can be used to show the level of intoxication considering it is where the most drugs with higher concentration are present. Despite many variant factors like inability to correlate to the impact of the drug that is why it is important in doping and screening test.

According to the laboratory report from HSA has shown the presence of AM694. This means the controlled drug that was bought contains synthetic cannabinoid (CB) as shown in the HSA report. Hence, the controlled drug that was bought contained K₁ values for 0.08 for CB₁ and 1,44nM for CB₁. For the accuracy of the result, a hypergeometric sampling was used to analyze the bought controlled drug. Additionally, the result shows a 96% confidence level that the drug contains AM694.

Therefore, any person except for authorized by the Misuse of Drug Act (cap 185) shall be an offense either on his behalf or on behave of another person whether the person is in Singapore or not. Accordance to section 33A the person shall be assumed to have possessed the drug with the aim of trafficking. Moreover, as per the 3^rd Schedule of MDA, punishment is five to seven years imprisonment accompanied by three to six strokes.

Avoid touching the evidence with bare hands.

Another practice that would minimize contamination is removing the DNA that is not wanted. Removing contaminant that is related to PCR

Kastie-Meyer test

Leucomalachite Green (LMG) test.

The reason the presumptive test gave a negative result because the blood was not human or the result was affected by other substance to give a false result so the confirmatory test was done to confirm if the result was really home.

The security features commonly found in passport, certificate, and banknotes are; watermark, security thread, security ink, luminescent and colored fibers, and Micro-printing.

SECTION C

Question #3 Q 3.1

Trace evidence is that physical evidence such as hair, glass and much more material that can be induced by friction when the bodies are in contact or through heat. In most cases, the trace evidence is always in a small amount at the crime scenes. The most used tools in visualizing of trace evidence are Microscope, Stereomiscrope, scanning electron microscope, and comparison microscope. In this case, the examiner of trace will be looking for microscopic elements to be collected from the scene of the crime and therefore, the black fibers would be the perfect trace evidence to start with.

Trace Evidence Interpretation

Q3.2

According to Lockard’s principle, it is impossible to be in contact with the environment and not to change it. Therefore, in the crime scene, there would be trace evidence as the environment can be changed through addition or removal of something. The transfer of trace evidence depends highly on the medium. For instance, black fibers in the crime scene were considered to be unique as it was the only foreign material in the scene. Most of the forensic experts agree that human beings are frequently and habitually in contact with fibers and this shows why black fibers were the first trace evidence to be suspected.

Primarily, the trace evidence is affected by factors like the nature of the trace, nature of the contact surface, amount applied on contact and external disturbance of the contact. There are many studies on numerous articles that explain how different fabrics determine the transfer and persistence of trace evidence.

Where to look for trace particulate in the crime scene would play important role in finding more evidence for the investigation. Forensic would need to combine both scientific knowledge and ingenuity to be effective in collecting the sample evidence. For the effective collection of the sample, forensic science ought to have applied three ‘R’.  The first ‘R’ is for recognition. Just after the crime scene, the trace must be recognized.  In this crime scene, the trace evidence like black fibers, blood on the knife and the hammer will be important as it will give sight for step two.

The second ‘R’ is for the record. In the crime scene of Mr. Lim’s death, it will be important to record all the trace evidence that include smeared blood and black fibers.  The reason for recording is to make sure the forensic has the required information of the evidence before it is contaminated by either human or environmental factors. The last ‘R’ stands for recover. After the trace evidence is recorded, it is taken to the laboratory to be visualized by using of hand lens or microscope for further details concerning the case study.

Q3.3

Every contact leaves a trace and this is where the three ‘R’s of trace evidence is applied. Just after the evident, the trace must be recognized first. Aside from the black fibers found in the scene as the trace evidence, it will be important if some of the trace evidence is recognized as it to add more information of what really happened. For that to happen some of the trace evidence from the knife, handle smeared with the blood and shoeprint near the body should be taken into consideration. The second step enables all trace evidence found in the crime scene to be recorded before it is contaminated. The contamination of the trace evidence is not only through touching with bare hands but it is contaminated by the external factors.

Q3.4

The bloody shoeprint at the scene will be classified as a 2-dimensional impression as it did not vintage permanently on the surface of the crime. Moreover, as the second-dimensional impressions, its details will be affected by the material that is on the surface.

Q3.5

The use of light illuminations can be used to enhance the bloody shoeprint. Example of light illuminations is fluorescence light. In addition, the lifting technique may be applied. Lifting technique include electrostatic lifting and gelatin technique. However, in the case of the 3-dimensional mark, ‘dental stone casting material’ can be used to recover possible impressions. As the dental stone casting method can be destructive it is encouraged to photograph first before casting.

Q3.6

The first step the examiner should ensure is to recognize the impressions. The recovery of impressions will require a combination of experience to be recovered like ingenuity and case information.  Where there is a large volume of foot traffic, it may not be that useful to search for recovery footwear mostly in serious crime. However, in a crime scene with a low volume of foot-traffic, the examiner should make sure recovery of the mark does not affect the physical evidence.

Q3.7

By definition, General wear is the footwear or another type of wear expected to fade away when it is in contact with the surface. However, the general wear can be affected by the behavioral factor of wear and composition type. Such wearer includes tire and the type of shoe.

Q3.8

The identification of the pair of shoes will depend on the shoeprint information and in the case where the mark impression is of low quality the conclusion will be inconclusive and will be tendered by the defense. Moreover, if the impression is of high quality then it will offer reliable support to the case as evidence.

QUESTION 4

Q4.1

The contribution of pathologists in the scenes of suspicious death and homicide may have a positive impact on the case study various ways. The first impact will be the recognition of the evidence to be collected as the documentation of biological evidence at the scene will be done in a careful manner. When the evidence is located, the forensic pathologist will observe the evident with utmost scrutiny to see if some of the important pieces are missing. In addition, he will recommend the appropriate practice for preservation and collection of biological evidence.

During the crime scene processing, the forensic pathologist would understand and then advice on potential values of each biological evidence to the investigation. Most importantly, the forensic pathologist would ensure good communication between the crime scene and the crime laboratory.

In essence, the presence of forensic pathologist in the crime scene will enable easy documentation of the record and the connection with physical evidence. Aside from recording, the forensic may decide to take photographs as the visual record of the crime scene.

The other importance of forensic pathologist in homicide and in suspected murder crime scene will be to ensure irrelevant matters are not presented to the biological evidence during or after the crime had taken place. Lastly but not least, the presence of pathologist in the crime scene will enable most accurate autopsy record as the information is given on the case will be first hand and very reliable. Concluding, forensic pathogens will contribute to the attending of the crime scene of a homicide or suspected deaths.

Q4.2

Since the autopsy reports contain both external and internal examinations, this information on the report will provide more details on the investigation. In this case of Mr. Lim death, the external injuries like a severe wound to the head will try to explain the cause of death or the manner of death in the investigation. However, the deep circular depressed fractures in the skull which is almost 2 cm in diameter will probably be caused by a heavy and sharp object like a hammer. In addition, the fracture in the head will be caused by the second party and these details will classify the case as homicidal.

Q 4.3

It is a forensic method in the investigation of criminals. However, there still concerns proliferation in the used technique despite being used for last decades. When reviewing DNA profiling as evidence by advocate or court, one can never be overemphasized that great care should be taken as it provides essential facts on the case. In addition to it is confidentially in the investigation, the forensic scientist collecting the sample when seeking to understand the process, process and proving should make sure the sample is carefully evaluated. Nonetheless, the advocate had to ensure careful scrutiny of interpretation of DNA profile is introduced to the court

In essence of Mr. Lim and Mr. Martins case for DNA profiling to be used, first, it is important to understand what makes a person ‘unique’.  Earlier, for a human to be identified there were only two information needed which include the characteristic of the individual and the frequencies of those characteristics. The knowledge characteristic frequency was based on the assumption that characteristics are independent. Moreover, the assumption on this information was only less prejudiced if the frequencies were reduced by adding more characteristics.

The discovery of DNA profiling out-rooted the other the information on frequency characteristic and the use of the blood group as it is what really easy to explain what makes ‘person’ unique. The even identical twins who are monozygotic have different genetic markers and due to this forensic is be able to answer the question from individuals who ask for uniqueness in DNA profiling.  Therefore, for us to understand human profiling in Mr. Lim and Mr. Martin’s case it will be better for us to understand what DNA extraction is.

In DNA extraction, substances that contain cells containing nucleus have a high possibility of containing extractable DNA. In substances like blood, bone tissues, urine and hair are few of places where DNA will be extracted. The extraction of DNA needs tools and kits that depend on cost evaluation and the use of hazardous chemicals. The blood stains from the crime scene will be extracted from the hammer and the knife by DNA-IQ extraction techniques especially. The released DNA from both items will bind to silica beads and denatured proteins since cell debris will be washed away.

The quantity of the DNA that will be extracted from the hammer and the knife will depend on the type of tissue. The need to validate and implement the crucial as it is important in determining whether the DNA is human or if the amount of DNA extracted is sensitive to STR-PCR kits. The PCR is occasionally inhibited by the forensic samples due to the environmental exposure that causes DNA degradation. Quantification as the process can provide the approximated level of inhibition present in the sample or degradation level in the sample.

 Due to an easy methodology of PCR, it will be the best technique for DNA amplification. There are other methods of DNA amplification that include amplification of STRs and PCR. In Mr. Lim and Mr. Martins case, it will preferably be better to use PCR as the forensic community favors it for its simplicity and accuracy.

The interpretation of the DNA profiling in Mr. Lim’s case will give facts on the murder weapon used. The profiling of the DNA from the DNA found on either the knife or the hammer will be compared with the reference profile to see if there is a match, and if they are not, the exclusion will be applied. If the DNA profiling matches the suspect, in this case, assumed to be Mr. Martins then inclusion will be applied. However, the significance of the match will depend on the presentation and calculation probability.

DNA profiling has various importance as it can be used as a tool in the criminal justice system and it can be used to determine the suspects liked in the crime like in this case Mr. Martins. However, the errors in dealing with DNA evidence could be used to form “Compound Error Effect”. Additionally, it will be important to also consult the article when dealing with DNA evidence as it is also important to the investigation of Mr. Lim case.

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