a. Propose the type of sampling (from the left column of the table below) to be used foreach of the five different exhibits (in right column of the table) to best respond to the question of whether a controlled drug is present in the said exhibit.
Explain your choice(s) for the type of sampling for each exhibit. You may choose the same type of sampling multiple times. You do not need to use all types of sampling.
b. Explainthe advantage(s) and disadvantage(s) of non-statistical and statistical sampling, by providing
Describe the general process of urine testing for controlled drugs in the laboratory and identify the relevant procedures the laboratory should take in order to comply with the testing procedure as stipulated under section 31 of the Misuse of Drugs Act (Cap.185).
In a sexual assault case that occurred in a hotel room, the victim reported that her attacker licked and raped her. In the following scuffle, she was able to injure him using his own knife, after which he ran away.
a. whichexhibits are to be collected and all the laboratory tests which are to be conducted on the different collected exhibits; and
b. theprocedures which the scene-of-crime-officer needs to follow when collecting the evidence.
Identify, in detail, the challenges a DNA analyst has in the interpretation of DNA profiles.
Mr Goh of Company A reported to the police that he suspected the business contract between him and Mr Lee of Company B had been altered. He claimed that paragraph 10 about profit shares on page 3 of the contract was not present when he signed the document.
The police sent the document to you, and as a Forensic Document examiner, you found that:
Formulate your explanations on the types of examinations you will conduct and state the reason(s) why you would conduct these.
1. a. In order to identify of a controlled substance, two tests must be performed. One test is a screening or presumptive test and the other test is an instrumental or confirmatory test. The tests are conducted to confirm the presence of drug in the sample by comparing it with a known standard of that drug.
Exhibit (1) matches A as it contains pharmaceutical preparations, hence, the administrative sample selection shall be used. Since there is no presence of amphetamine and opiates, it does not require a weight and any recorded weight is not required to be reported.
Exhibit (2) matches B and Threshold sample selection shall be used as sufficient material is present to satisfy the statutory threshold and there is a possibility of individual analysis of the units.
Exhibit (3) matches C and hypergeometric sampling plan shall be used as there is sufficient material that meets the statutory threshold but analysis of the units is not practicable. If analysis confirms presence of controlled substance, the average weight of the three analyzed units shall be determined.
Exhibit (4) matches D and statutory threshold sampling plan shall be used as there is sufficient material to meet the statutory threshold and it is not practicable to analyze the units.
Exhibit (5) matches E and Hyper geometric sampling plan shall be used as although sufficient material to meet the statutory threshold but it is not practicable to analyze the units. Further, this sample is used to inspect the size, weight, tampering of the exhibits.
b. The advantages of statistical sampling is that it enables the auditor to design an efficient sample; evaluate the sample results quantitatively and assess the authenticity and adequacy of the evidence obtained. A statistical sampling uses the probability of laws in order to measure the sampling risk. The disadvantages of statistical sampling as the result are presented as range of values or figures instead of one answer. The sampling process involves several steps and if such processes are not done correctly, it may lead to invalid or incorrect results.
Any sampling procedure that does not measure risks is known as non-statistical sampling process. It is advantageous mainly because it involves simple evaluation, low sample selection expenses and cost of training is lower than the processes involved in the statistical sampling plan. However, it suffers from deficiencies such as it is haphazard, increase in the training expenses and ready availability of computers have also mitigated.
2. Urine testing- a urine drug test is usually conducted to determine whether there is a presence of certain illegal drugs in the body of the concerned persons. Under section 31 of the Misuse of Drugs Act if any officer or immigration officer or police officer not below the rank of sergeant reasonably suspects any person o have committed an offence under section 8(b) of the Act, that person is required to provide a specimen of his urine for conducting urine tests under this section. The laboratory specialists shall divide the specimen of the urine into three parts. A preliminary urine tests shall be conducted on part of the urine specimen and each of the remaining 2 parts of the urine specimen shall be marked and sealed and a urine test shall be conducted by either an analyst employed by the Health Science Authority or any person authorized by Minister. The regulatory procedures that must be followed by the laboratory include the regulations related to:
- Urine tests and sample
- Procurement of the urine sample
- Collection and delivery of the urine samples and preparing security arrangements
As per First Schedule with respect to the procurement of urine specimen, the suspect shall be provided with a master bottle. The containers shall contain the name and NRIC or other ID of the suspect which shall be duly signed by the suspect. The officer shall deposit the container to the HSA. The laboratory officers shall perform the Presumptive tests in order to detect drugs such as opiates, amphetamines, morphine, thereafter, the rapid test shall be conducted using GC-MS or LC-MS/MS and majority of samples that shows negative results for drug abuse shall be eliminated. By using the Mass Spectrometer (MS) it forms the basis for identifying the drugs as it compares the drug with a reference drug material. The test results are supervised by the analysts and the analyst-in charge analyses and construe the test outcomes. If any controlled drug is found in the urine tests conducted under section 31(4)(b), the person shall be presumed o have consumed controlled drug which amounts to violation of section 8(b) of the Act.
3. a. Under the given scenario, the exhibits that are to be collected include the following:
- Blood droplets
The laboratory tests which are to be conducted on the above collected different exhibits include
- DNA profiling
- Semen confirmatory test
- DNA test of blood droplets on the knife
- Polymerase chain reaction (PLC) for analyzing saliva
b. The scene-of-crime-officer must be methodical while collecting evidence from the crime scene. The officer must ensure that the crime scene is secured and the evidences at the crime scene are protected from being contaminated. The officer shall safeguard biological evidences as they are likely to get contaminated faster than the physical evidences. Such evidences must be properly sealed and transferred or delivered to the laboratory safely and any third person shall be prevented from tampering with such evidences.
4. Although forensic science plays an important role in resolving crimes and assists the courts to administer justice to the victim, the forensic aspect suffers from certain deficiencies. There have been instances where individuals have been wrongly convicted owing to various reasons. The forensic scientists often experience a cultural clash between law and science. In other words, the legal community uses previous judgments or precedence in their arguments whereas the scientific community relies on the future improvements. Further the legal community is more concerned with the final and absolute decisions that is, guilty or not-guilty court decisions.
On the other hand, the scientific community performs their tasks without any certainty that is; they function rarely with the probabilities of 0 or 1. Furthermore, it has been observed that often the scientists and the lawyers talk past each other merely because they fail to appreciate any significant or subtle difference in the meaning of any phrase or word. For instance, the term ‘validity or validation’ can be interpreted differently by lawyers as compared to the forensic practitioner and scientists.
The essential element that the scientist involves in any case is the correct interpretation of the observations and it is considered as the cornerstone of forensic science. This procedure is fundamental as it adds value to the forensic process. According to Louis Pasteur, chance favors the prepared minds in the observation procedure. DNA analysis is one of the most useful forensic disciplines. The DNA profiling enables the forensic scientists to detect the accused in violent crimes such as rape and murder. The interpretation of all the forensic evidence entails comparing question results with known references and this comparison depends on the result quality that is obtained from the evidence and samples collected from the crime scene.
The challenges that are faced while conducting DNA analysis include the sample backlogs and inappropriate data interpretation. The expert system data review and laboratory automation as well as stringent acceptance policies can be used to reduce sample backlogs. The crime investigators often provide numerous items to the forensic scientists without thinking whether such items would be probati. Data interpretation errors are most likely to take place under situations which involves DNA mixtures from three or more individuals, with low-template DNA touch samples, in particular. The inconvenience in dealing with DNA interpretation of complex mixtures results in reproducible results that are obtained from several forensic laboratories and/or forensic laboratories.
5. The crime investigator may obtain important information from the documents related to any civil or criminal case. The discipline of forensic document examination is known as ‘questioned documents’. The questioned document includes contracts, wills, seals, stamps, machine-generated documents. In this given scenario, the questioned document include contract that was entered into between Mr. Goh of Company A and Mr. Lee of Company B. Mr. Goh claimed that paragraph 10 about profit shares that was stipulated on page 3 of the contract was not present when the document was signed by him.
In order to conduct forensic examination of the documents evidence may be collected from the stamp impression, using an Electrostatic Detection Device (EDC) which is used to detect indented impression that is not visible to the naked eyes. Any form of alterations and erasures that is not visible to the naked human eye can be often detected using photography and other imaging devices that uses infrared and ultraviolet wave length of light to detect such alterations and erasures. The contract between the contracting parties entails a stamp impression which can be identified using the detection device.
In order to assist the examiner to detect the same, any suspected device that is related to the questioned document must be provided to the examiner, such as rubber stamps, printing devices, sealing devices or any other form of devices. The alteration of paragraph 10 in the contract can be detected using the EDC and an imaging instrument such as a video spectral comparator (VSC). It would reveal writing, if it has been added with a different ink or has been altered or removed by distorting the difference that exists in the way different ink respond to the different wavelengths of the light.
The printing process used to create the contract can be identified from the typewriter, laser printers, and photocopier and fax machines. While conducting examinations, forensic document examiners must possess known specimens to compare the material in question. For determining the contract which has been printed, the examiner may rely on the various databases created for the purpose of comparing with the material in question. The contract being machine printed documents; the machine itself must be submitted for examination.
Both the parties to the contract have signed the contract and in order to examine the handwriting, the investigator should obtain writing samples which are similar to the document in question. Not every person writes machine-like precision every time and there remains certain variations in the handwriting of the person even with the same document. Here the signature of both the parties that is present in the pages of the contract shall be examined.
Buckleton, John S., Jo-Anne Bright, and Duncan Taylor, eds. Forensic DNA evidence interpretation. CRC press, 2016.
Bu?, Magdalena M., and Marie Allen. "Collecting and preserving biological samples from challenging environments for DNA analysis." Biopreservation and biobanking 12.1 (2014): 17-22.
Butler, John M. "The future of forensic DNA analysis." Phil. Trans. R. Soc. B370.1674 (2015): 20140252.
Butler, John M. Advanced topics in forensic DNA typing: interpretation. Academic Press, 2014.
Christensen, Angi M., et al. "Error and its meaning in forensic science." Journal of forensic sciences 59.1 (2014): 123-126.
Edmond, Gary, et al. "Admissibility compared: the reception of incriminating expert evidence (ie, forensic science) in four adversarial jurisdictions." (2014).
Giles, Audrey. "8 Forensic Examination of Documents." Crime Scene to Court Fourth Edition: The Essentials of Forensic Science (2016): 229.
Lewis, Jane. Forensic document examination: Fundamentals and current trends. Elsevier, 2014.
Martire, K. A., et al. "On the interpretation of likelihood ratios in forensic science evidence: Presentation formats and the weak evidence effect." Forensic science international 240 (2014): 61-68.
Materazzi, Stefano, et al. "New insights in forensic chemistry: NIR/Chemometrics analysis of toners for questioned documents examination." Talanta 174 (2017): 673-678.
Ostojic, Lana, and Elisa Wurmbach. "Analysis of fingerprint samples, testing various conditions, for forensic DNA identification." Science & Justice 57.1 (2017): 35-40.
Robertson, Bernard, George A. Vignaux, and Charles EH Berger. Interpreting evidence: evaluating forensic science in the courtroom. John Wiley & Sons, 2016.
Saferstein, Richard. Forensic science: from the crime scene to the crime lab. Pearson, 2015.
Vidaki, Athina, Barbara Daniel, and Denise Syndercombe Court. "Forensic DNA methylation profiling—Potential opportunities and challenges." Forensic Science International: Genetics 7.5 (2013): 499-507.