Forensic Science - the Art of Blood Drop Reading - Assignment Example

RUNNING HEAD: FORENSIC SCIENCE Forensic Science By Q3 A: Three of the blood type patterns are: passive; transfer, and; projected.1. Passive 2. Transfer 3. Projected Passive bloodstains are drops of blood created solely by the force of gravity and include drops, clots, flows and pooling. They indicate lack of struggle. Transfer bloodstain include wipes, swipes, pattern transfers and other contact stains indicating the contact of a surface free of blood with another that has blood. Lastly, projected bloodstain includes spatters, splashes, cast-off stains and arterial spurts and indicate that force, greater than gravity, was used on a blood source (Murray 2005). One high profile case where BPA had helped in its resolution was the 1984 case of Graham Backhouse in England. A man named Bedale-Taylor lay dead shot by Backhouse’s shotgun. Backhouse claimed that Taylor entered unauthorized into his home and tried to kill him with a knife and so he was forced to shoot him. Backhouse himself sustained injuries on the chest and face. However, BPA analysis determined that the victim’s hands were covered with blood but not the knife, which did not sustain Backhouse’s claim that the victim attacked before he shot the victim. The blood splatters on the floor were round splashes which did not indicate that a struggle occurred because their shapes would have been exclamation-mark shapes. In addition, some of the furniture that got knocked down landed on top of blood splatters and blood smear was found on top of a fallen chair from Backhouse’s hand, yet there was no blood on the gun (Ramsland 2010). Q4 The Hardy-Weinberg Law is a formula that makes possible the measurement of the numbers of genotypes and alleles in a population without having that population undergoes DNA testing. This law states that both allele and genotype are in a constant equilibrium unless influences are introduced into the population that disturbs it and the Hardy-Weinberg formula to determine the likelihood that a suspect would share the sample DNA taken from the crime scene (Hunter 2006). On the other hand, the Product Rule is a formula for calculating the probability that a match between a DNA sample taken from the crime scene and of the suspect would occur only by chance. When a match between two samples are made, the math may either indicate that the suspect is guilty or that the DNA match was mere coincidence, in which case both the Hardy-Weinberg equilibrium and the Product Rule are used to calculate the weight of the match or the chance (Brenner 2010). Q5 Real-time PCR (RT-PCR), also known as Q-PCR (for quantitative) is a laboratory tool in DNA testing that allows the simultaneous detection and quantification of specific sequences in a DNA sample. Its value in forensic laboratory is that it males DNA testing faster and more precise. Q6 (1) STR Analysis assesses different regions or loci in the DNA, discriminating one region from another and establishing that the possibility that two persons could share the same 13 loci DNA profile is one in a billion or more. The FBI has adopted the 13-loci DNA profile of the STR as its standard in processing forensic or convicted offender. (2) RFLP or Restriction Fragment Length Polymorphism is the older technology in DNA analysis, but it was the first DNA profiling tool and was used by the FBI in DNA encoding. Q7 There is a move today in various states all over the country to expand the collection of DNA from convicted persons to even those who are legally innocent. At present, 15 states are already collecting DNA samples from persons arrested and are awaiting trial and detained immigrants. This is anticipated to increase the DNA bank of the FBI, who is joining the fray, to 1.2 million entries a year (Moore 2009). The main argument for this new legislation is that it will help solve more crimes as well as identify the guilty from the innocent more effectively. However, it is also contended that it is also a violation of the Fourth Amendment, collecting DNA being within the ambit of the term “search” as contemplated by the said Amendment. Collecting from convicted felons are justified by the significant benefit that such will give to public order and security but the same justification cannot stand in if the same is done upon persons not convicted of crimes. Q8 a. Sedatives, e.g. benzodiazepine b. Hallucinogens, e.g. LSD; Presumptive testing: emits blue fluorescent when dried on a filter paper and observed under a UV light. Laboratory Test: Using Ehrlich’s reagent test, blue or purple color shows if LSD is present. c. Stimulants, e.g. cocaine. Presumptive Test: The Mandelin Test that uses ammonia vetavanadate and sulfuric acid will produce an orange color for ammonia. Laboratory test: hair test, urine test d. Narcotics, e.g. diacetylmorphine Q9 The age of the document could be determined by identifying the additives, watermarks and surface treatments, because it will indicate the date or year such paper was introduced. In addition, the ink used in the document should be identified using microspectrophotometry to know the absorption spectrum or thin-layer chromatography (TLC) to identify the exact composition, and find a match for it in the ink database of the US Bureau of Alcohol, Tobacco and Arms (Ramsland 2001). TLC is conducted by separating the dye of the ink used in the document and comparing it either with an ink sample manufactured 30 years ago, or if not with the ink of an authentic document 30 years old. The benchmarks should be: color; distance travelled from one origin to a point; shape; and relative intensity (Levinson 1318). Q10 Fig 1. The presence of petechial hemorrhage in the conjunctiva of the eye may indicate asphyxiation by strangulation, hanging or smothering. The hemorrhage occurs when blood leaks from the capillaries of the eye due to their rupturing from increased pressure on the obstructed airways of the veins of the head. Fig 2a,b A dark red discoloration appears on the upper portion of the torso particularly on the right but some other parts of the body are pale especially in the chest area and some parts of the inner arms. The dark red discoloration is caused by capillo-venous distention and is called post-mortem staining or hypostasis. This is often caused by circulatory failure such as during congestive cardiac failure. This observation is buttressed by the presence of pale portions of the body caused by the pressure of the arms against the chest, perhaps when the victim clutched his chest as he was having a heart attack. Fig 3 Blood spatter, with preponderant stain as small as 1mm in size or smaller indicates a high impact, high velocity impact spatter produced by a force of 100 feet/sec and greater. This indicates the use of a high impact, high velocity weapon like a gun. This does not seem to be a case of suicide because the wound is clean and no ring of lead or smoke surrounds it. A gun fired more than 3 feet, which precludes suicide, does not show presence of gun residue on the victim. Fig 4 The wounds are obviously self-inflicted considering that they are found on the inner left arm and run diagonally from the low left to the upper right side, consistent with a person holding a knife or a paper-cutter, as in this case, on his right and slashing his left arm. The placement of the wound in the picture is the easiest way to inflict wounds to oneself and difficult if done by another party: inner arm rather than the outer; diagonally from the left to the right, and from down up. Q11 The top half provides the following information: Y-STR markers of paternal chromosomes, with the number of alleles indicated in each locus. A neophyte DNA analyst should ask himself/herself if the sample at the bottom could be useful as comparative basis to the given sample at the top considering that in locus DSY91of the bottom sample allele 11, which is rare recurring, appears. On the other hand, the presence of very few alleles in each locus does not seem to make the sample significant and useful. Q12 (a) [1] Lineage Informative SNP, [2] Phenotype Informative SNPs (b) Phenotype characteristic is the consequence of genotype characteristics. This is because genotype refers to the genetic make-up of an organism or a group of organisms while phenotype refers to the appearance of the organism, which is a result of the genotype interacting with its environment. Genotype produces organism traits such as features, attributes or characteristics handed down by the through the genetic code while the characteristics that constitute traits such as height, coloring and lactose intolerance are each considered a phenotype. Thus, phenotype is measurable, apparent and observable characteristics as opposed to the unobservable and latent nature of the genotype. Genotypes are modified by the environment and the conditions present during a person’s development and persons with the same phenotype do not necessarily have the same genotypes (Slater & Bremner 71). Alleles are gene versions that are responsible for hereditary variation and are useful in identification because if found at the scene of the crime can lead confirm or exclude the presence of the suspect. If the suspect’s allele matches the sample, and such allele proves to be rare in the population, then the evidence against him carries weight. (c) [1] SNPs are more frequent and therefore, provide a dense marker spacing; [2] although found in non-coding regions, some SNPs are located in genes and can be identified as potential disease variations; [3] SNPs are more stable (Ziegler & Konig 56). (d) The female sex can be eliminated on the basis of the DNA sample. The loci are: DYS393; DYS19; DYS391; DYS3891; DYS38911. References: Brenner, C. (2010). Forensic Mathematics of DNA Matching. http://dna-view.com/profile.htm. Hunter, P. (2006). All the Evidence. EMBO Reports. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1456910/. Levinson, D. (2002). Encyclopedia of Crime and Punishment, Vols. 1-4. SAGE. Moore, S. (2009). FBI and States Vastly Expand DNA Databases. New York Times. http://www.nytimes.com/2009/04/19/us/19DNA.html?_r=1. Murray, D.C. (2005). Bloodstain Pattern Analysis Tutorial. http://www.bloodspatter.com/BPATutorial.htm. Ramsland, K. (2010). Blood Pattern Analysis. TruTV Crime Library. http://www.trutv.com/library/crime/criminal_mind/forensics/serology/4.html. Ramsland, K (2001). Forensic Science of CSI. Penguin. Rao, D. (2010). Post-Mortem Hypostasis. Forensic Pathology. http://www.forensicpathologyonline.com/index.php?option=com_content&view=article&id=54:post-mortem-hypostasis&catid=49:chapter2-cat&Itemid=116. Siegler, A. & Konig, I. (2002). A Statistical Approach to Genetic Epidemiology: Concepts and Applications. Wiley-VCH. Slater, A. & Bremner, J.G. (2003). An Introduction to Developmental Psychology. Wiley-Blackwell. Read More