Dna in criminal justice_complete slides

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Dna in criminal justice_complete slides

  1. 1. 1
  2. 2. Science and law are two distinct professions that are increasingly becoming co-mingled as technology develops (Bezak, 1992) Science Law Techniques to identify criminals have evolved at a fast pace because of science. biological markersEyewitness-dependent identification DNA anthropometry fingerprinting fingerprinting 2
  3. 3. What pushed the paradigm shift from eyewitness accounts to biological markers approach to criminal identification?The impetus behind the development of biometric criminal identification technologies in the late nineteenth century include factors such as rapid urbanization; the increasing anonymity of urban life; and the dissolving of local networks familiarity in which individuals were “known” by their neighbours (Cole, n.d.) 3
  4. 4. AnthropometryAnthropometry is a system The Bertillon system was using body measurements generally accepted for thirty of adult individuals for years (German, 2012). personal identification (Moenssens, 2008). Photographs and anthropometric descriptions are used at a later time to identify a criminal, thus establishing hisIt relies on the taking of the criminal history. measurements of bony parts of the body, including DOWNFALL: measurements of the cartilaginous human ear. 4
  5. 5. FingerprintingThe downfall of His report is anchored on the anthropometry was used in documentation of 22 cases, the rise of newer technology most involving violent crimes, in called fingerprinting. which fingerprint evidenceGerman (2012) called this as turned out to be dead wrong. the beginning of “fingerprinting as infallible Dye (2005) further iterated, means of personal however, that the fingerprints identification” did not lie; rather the experts who matched them with aDye (2005) reported that a suspect were wrong. study showed fingerprint evidence is not infallible. 5
  6. 6. DNA Fingerprinting Many highly polymorphic minisatellite loci can be detectedGenetic information was simultaneously in the human genome by hybridization to probes consisting of tandem repeats of the core sequence. of seemingly peripheral interest to The resulting DNA fingerprints produced by Southern blot hybridization are comprised of multiple hypervariable DNA forensic scientists for fragments, show somatic and germline stability and are a number of years completely specific to an individual. (Saferstein, 2006) We now show that this technique can be used for forensic purposes; DNA of high relative molecular mass (Mr) can be isolated from 4-yr-old bloodstains and semen stains made onIn 1985, this changed cotton cloth and digested to produce DNA fingerprints when Alec Jeffreys suitable for individual identification. reported in the British Further, sperm nuclei can be separated from vaginal cellular Nature Journal the debris, obtained from semen-contaminated vaginal swabs, enabling positive identification of the male donor/suspect. Forensic application of DNA fingerprints It is envisaged that DNA fingerprinting will revolutionize forensic biology particularly with regard to the identification of rape suspects. 6
  7. 7. Pate (n.d.), Vaca (1995) and Saferstein (2006) reported that this process was the first scientifically accepted protocol in the US for forensic characterization of DNA. 7
  8. 8. Semikhodskii (2007) describes the question whether or not DNA evidence on its own is enough to convict an accused as one of the most talked about points regarding evidence.Thompson (2008) in his paper for the Council of Responsible Genetics entitled “The Potential for Error in Forensic DNA Testing (and How That Complicates the Use of DNA Databases for Criminal Identification” argues that forensic DNA testing may bring about false incriminations by means of (1) coincidental profile matches between different people; (2) inadvertent or accidental transfer of cellular material or DNA one item to another; (3) errors in identification or labelling of samples; (4) misinterpretation of test results; and (5) intentional planting of biological evidence. 8
  9. 9. In 2009, Victorian Police Commissioner Simon Overland to order his officers to stop giving DNA evidence in court proceeding over concerns about discrepancies between the science and interpretation of samples.Cole (n.d.) highlighted the objections against DNA databases taking grounds on (1) the threat of eugenics; (2) reliability of forensic evidence; and (3) breadth of databases. 9
  10. 10. Based on case readings, doubts fall into the following themes: 1) coincidental profile matches; (2) unintentional attribution of DNA profile to another; (3) unfounded threats like planting of evidences and eugenics; and (4) breadth of database. Of these four, only the first can be deliberated within the world of “pure” science thereby crediting such doubts to DNA technology itself. 10
  11. 11. Coincidental Profile Match In the cases Thomson reviewed for the past years, evidentiary samples from crime scenes are reported to be often incomplete or partial DNA profiles. Limited quantities of DNA can make it impossible to genotype at every locus (STR uses 13 loci as markers). In some instances, the test yields no information about the genotype at a particular locus; in some instances one of the two alleles at a locus will become undetectable. Koehler (1993) supports that because partial profiles contain fewer genetic markers than complete profiles, they are more likely to match someone by chance. 11
  12. 12. Profile B and C are examples of partial DNA profiles. In both cases these partial profiles would be deemed to “match” Profile A because every allele in the partial profiles is also found in the full profile. Hence, we have a coincidental profile match brought about by partial DNA profiles. 12
  13. 13. Landmark cases of coincidental match: US. BBC News (2007) reported that in 1999, in Swindon, a man with Parkinsons Disease was arrested, and charged with a burglary in Bolton. He was frail and had never been there. But his DNA sample matched one taken from the crime scene (a 6 locus partial DNA as evidence). Similarly, in 2004, Sweeney and Main reported in Chicago Times that botched DNA six locus partial DNA profile report falsely implicates a woman. A as evidence was compared against a state offender database. When the search produced a hit, the police arrested the woman but she was eventually released considering a strong alibi of being in the custody of a state prison at the time of burglary. 13
  14. 14. Unintentional attribution of DNA profile to another Unintentional attribution of DNA profile to another could be brought about by cross-contamination of samples, accidental transfer of DNA from one sample to another, mislabelling of samples, and misinterpretation of samples.Landmark cases: Rape Case: Brian Kelly in Scotland Murder of a toddler Jaidyn Leskie in Australia 14
  15. 15. Eugenics The argument is based on George Annas “genetic exceptionalism” concept (Thompson, 2008). Genetic identification was distinguished from supposedly harmless biometric identification technologies like fingerprinting. Simply put, unlike fingerprints, genes contain information about an individual’s racial and ethnic heritage, disease susceptibility, and even behavioural propensities. The author put it simply with “insurance companies, employers or other government agencies might raid the data for health-related data, leading to genetic discrimination against individuals or groups. 15
  16. 16. Gans and Urbas (2002) maintain the benefits of DNA identification in the Criminal Justice System. They presented twelve significant Australian DNA cases.One of which is that of Desmond Applebee within the Australian Capital Territory. This was the first use of DNA evidence in Australian criminal proceedings. The accused was charged with sexual assault and initially denied any contact. He altered his defense to consensual intercourse after DNA evidence was admitted as part of the case. He was eventually convicted by the jury. 16
  17. 17. In light of the issue on coincidental profile match, Kaye and Sensabaugh (2000) and Freckelton and Selby (2000) advocate ways to reduce error. The number of DNA features profiled can be increased. Similarly, possible suspects can be tested or excluded by mass screenings or database searches.As previously noted, unintentional attribution of DNA profile to another could be brought about by cross-contamination of samples, accidental transfer of DNA from one sample to another and mislabelling of samples. Errors brought by these unintentional attributions can be reduced by separating the profile of suspect and crime samples. In addition, stringent crime scene and laboratory protocols can be introduced to avoid contamination. And if possible, a part of the crime sample could be preserved prior to testing. 17
  18. 18. Contrary to eugenics, the National Institute of Justice (2000) and van Ooschot, et al. (2001) argue that the present limits of genetic science means that a direct analysis of a person’s DNA will yield only limited information about individual characteristics.As to the strength of DNA fingerprinting, there have been no known false DNA matches in Australia, but there have been noteworthy instances in other countries (the previously discussed cases in UK and Chicago). Similarly argued by Gans and Urbas is that the errors in the handling of samples or the reporting of results can be largely avoided through protocols. 18
  19. 19. Following Mueller’s conclusion, DNA typing can be a powerful tool in forensics (1993).The risks of false or misleading results attributed to DNA fingerprinting should not be considered as just cause to reject its use in criminal investigations and identification. This is most typical when there is independent evidence about a suspect’s guilt or innocence.Another concern highlighted by this review is the need for policies and protocols which would ensure that laboratories carrying out DNA fingerprinting would perform the tests with the highest accuracy possible. 19

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