Introduction
The use of deoxyribonucleic acid or DNA tool is one of the recent forensic science advancements that has improved criminal investigation and prosecution accuracy. Following an increase in the incarceration of innocent people due to mistaken identity, the criminal justice department has seen the importance of applying biological forensic in identifying crime (Farley, 2019). DNA has been applied in forensic science to determine the guilt or innocence of an individual. Advancement in technology has improved forensic biology, making it possible for the criminal justice department to solve crime cases committed for over 50 years. The adoption of forensic biology and establishments of labs to handle DNA evidence has helped solve thousands of cases, especially those related to rape, murder, and sometimes robberies. DNA technologies are increasingly improving criminal justice investigations and forensic science by ensuring accuracy and fairness in the criminal justice system (National Research Council, 2009).
Identifying DNA Evidence
DNA and biological evidence solve crime in two ways. The first case involves an identified suspect whose sample is taken and compared to DNA collected at the crime scene. DNA results determine whether the suspect is the actual criminal or mistaken identity (Vijay & Singhal, 2015). The second case involves an unidentified suspect. The officers use biological evidence collected from the crime scene to analyze and compare the offender's profile in the DNA database to ensure the right perpetrator gets punished (NCJRS, 2012). The method has effectively helped in apprehending criminals and preventing committing crimes in the future. Biological evidence collected can be in the form of semen, blood, saliva from cigarette, hair, vaginal secretions, urine, bone, and facial material.
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When identifying, collecting, transporting, and storing biological evidence obtained from DNA, the investigation team should be aware of important issues that account for reports' accuracy. During the collection of evidence, for instance, in sexual assaults, the victim should not change the clothes or wash any body parts. Evidence on sexual assault like semen, saliva, and body skin can be found on clothing, bedding, anal, vagina, or mouth areas; hence washing might contaminate evidence (Magalhães et al., 2015). Immediately after the evidence is collected, a medical examination needs to be conducted to treat any injuries, prevent sexually transmitted diseases, and gather adequate forensic evidence. The medical examiners also need to take reference samples from the victim's body, for instance, saliva, blood, and vaginal fluid, in case of rape to serve as a control standard. The victim must provide information about other people they have contacted, especially sexually, within 72 hours to avoid rule them out. Elimination samples are collected from consensual sex partners like respondents and others to exclude them from investigation Magalhães et al., 2015). According to Turman (2001), the victim's DNA is used to compare known DNA from that collected in the crime scene to determine possible suspects. The forensic examiner should correctly select materials for collecting evidence and dry them appropriately after packaging.
Crime Scene Integrity, Preserving, and Contamination of DNA
The protection of the crime scene is very crucial to evidence protection. When documenting crime scene evidence, a factual description of the nature of evidence, whether collected wet or dry, needs to be included. The investigation team requires a chain of custody, showing a list of persons who had physical possession of the evidence to maintain integrity (Turman, 2001). In case the lab test incubates contamination of evidence, it will be easy to determine the person who handled the piece of evidence. Owing to the sensitive nature of DNA and biological evidence, few individuals should be involved in the entire process to reduce the risk of contamination (Vijay & Singhal, 2015). All the steps from identification, collection, storage, and transportation of the evidence should follow the chain of custody to ensure integrity.
In forensic science, the greatest challenge or barrier is the contamination of biological evidence fpm other sources either when collecting or storing evidence. Once the evidence is collected, they need to be preserved well since they degrade fast when exposed to heat or humidity. If adequate protection measures are not taken during DNA evidence collection, it can easily contaminate other people's DNA, like officers collecting evidence. Criminal investigators are expected to wear protective equipment like disposable gloves and avoid touching other objects to handling forensic evidence (Magalhães et al., 2015). The forensic examiner needs to ensure the room where forensic material examination (FME) occurs is regularly cleaned and disinfected to prevent DNA samples' mixing. The team is not expected to touch any other object in the room or smoke, eat or drink when handling DNA evidence. Crime investigators should ensure biological evidence is thoroughly air dried, packaged in the right material, and labeled well (Turman, 2001). Well-handled and stored DNA evidence can stay for decades without degradation.
DNA Testing and Interpretation of Results
DNA profiling is based on the fact that no two individuals, except identical twins, possess similar DNA types. The likelihood of getting a DNA match between a crime scene center and an individual who is not the actual perpetrator is minimal. Based on the court report, approximately one individual in every 5 trillion randomly chosen would possess a similar DNA genotype as a person found in the questioned sample (National Research Council, 2009). Since there is no community or country with 5 trillion people, no two individuals share similar DNA genotypes. DNA testing must be conducted in the laboratory where facilities and personnel meet the FBI's requirements stringent QAS requirements. After performing the DNA analysis, initial testing needs to be conducted at the scene of a crime to determine the type of material been questioned (Forensic Science),
There are several methods of testing and analyzing DNA evidence in forensic science. The most common method is polymerase chain reaction (PCR), developed in the 1980s by Kary Mullis. PCR uses the ability of DNA polymerase to synthesize a new strand of DNA complementary to the template offered (Śpibida et al. 136). Polymerase chain reaction (PCR) allows criminal investigators to analyze evidence samples of all quality and quantity at ease. OCR analysis makes millions of copies of a small amount of DNA, allowing the forensic team to generate a DNA profile compared to the suspects' DNA sample. Once the profile is generated, a statistic is created, reflecting the probability of finding this specific DNA profile in the general population.
The DNA results are entered into the Combined DNA Index System (CODIS) to allow the investigation team across the country to share and compare DNA profiles to aid in investigating a particular case. CODIS operates under three levels; Local DNA Index System(LDIS), State DNA Index System (SDIS), and National DNA Index System (NDIS). DNA results in crime investigation fall under inclusion, exclusion, and inconclusive. An inclusion result occurs where the suspect's DNA profile is consistent with the DNA profile gathered from the scene of the crime (LaPorte 2017). "Exclusion" is the other interpretation where the DNA of the victim differs from the DNA collected from the crime scene. In this case, the investigation "excludes" the individual as the donor of the evidence collected, although exclusion does not necessarily mean the person is innocent. For instance, in a rape case, DNA of a condom may exclude the perpetrator, while DNA of the same person is found in other areas within the crime scene. The third DNA result is inconclusive, showing that DNA could neither include nor exclude an individual as a source of biological evidence. Inconclusive DNA result in forensic science is caused by insufficient quality or quantity DNA sample. The conclusive result might occur in crime investigation involving gang rape or robbery where the suspects and witnesses trying to save the victim touches similar objects or ground. Even after the release of DNA results, the investigation team needs to perform another testing to help interpret other evidence collected at the crime scene.
Benefits of DNA in Forensic Science
The use of advanced DNA technology like PCR helps crime investigators to obtain conclusive results where previous results have been inconclusive. Through this, the results obtained can be beneficial in solving previously unsolved cases. From the 1990s, news stories have extolled DNA's successful use to solve a crime that police officers had earlier failed to solve. In 1990, the New York criminal justice system used DNA evidence to successfully link a man to over 22 sexual assaults and robbery cases in the city (LaPorte 2017). By 2002, most states, including Philadelphia, Pennsylvania, and Fort Collins, had adopted DNA in their criminal justice departments to solve series of crimes. In almost 15 years, the DNA database in the USA has grown. DNA collection laws have been implemented to provide numerous samples to aid in testing (Farley, 2019). By 1999 only sexual assaults required a mandatory DNA sample, while in 2014, all states gathered DNA from all convicted felons.
Through the use of DNA, many innocent individuals have been exonerated after being wrongfully convicted. According to the innocence project, 342 individuals have been exonerated through DNA analysis, having served an average of 14 years in prison (Innocence Project). Out of these individuals, 55% of exonerees are African American, 38% are Caucasian, while 7% are Hispanics. Twenty-one of the exonerees were serving time on death row, 44 had pleaded guilty to a crime they never committed (LaPorte 2017). Most of these individuals, 69%, were wrongfully convicted due to the eyewitness's misidentification, 43% resulted from a misapplication of forensic science, while 29% was due to false confession (Innocence Project). Other causes of wrongful convictions include government misconduct, inadequate defense, weak prosecution case, states with punitive culture, and police misconduct (Hampikian et al., 2011). Out of 375 exonerated cases, 165 cases were closed after actual assailants were identified and convicted of additional 154 violent crimes.
Challenges of DNA and Biological Evidence and Proposed Solutions
The success of DNA and biological evidence in forensic science has brought significant change, leading to new challenges in confidentiality, backlogs, and interpretations. The major challenge facing the use of DNA and biological evidence in criminal justice is personal information privacy and confidentiality (Butler, 2015). The nature of DNA backlog comprising casework sample backlogs and convicted offender backlogs is complex making it challenging to change and measure the precise number of unauthorized DNA samples (Justice.gov, n.d). There is a high data interpretation uncertainty when using DNA, leading to errors, especially when DNA mixes from three or more individuals.
The issue of confidentiality of data is solved by applying quality assurance measures developed to ensure confidentiality of results obtained. The quality infrastructure of DNA testing in criminal investigations is promoted by organizations like the European DNA Profiling Group (EDNAP) and the European Network of Forensic Science Institutes (ENFSI) in Europe and the Scientific Working Group on DNA Analysis Methods (SWGDAM), and Federal Bureau of Investigation's DNA Advisory Board (DAB) in the USA (Butler, 2015). Backlogs' issue is solved by laboratory automation and expert system data review that applies restrictions ion case acceptance policies. The investigation team may conduct "swab-a-thorn" at the scene of a crime and gather other evidence, and use the DNA database to determine the facts (Justice.gov ). The challenge of error in data interpretation is solved by an increase in DNA detection sensitivity, which brings high responsibility in interpreting data.
Conclusion
In summary, DNA and biological evidence have improved the criminal justice system making it possible to arrest the real perpetrator and exonerate those wrongfully convicted. As technology advances, the use of DNA in forensic science improves and becomes faster, making it possible to solve thousands of cases in a day. There is a need to improve the ability to decipher and interpret DNA results gathered from challenging samples.
References
"Advancing Justice Through DNA Technology: Using DNA TO SOLVE CRIMES". (Justice.Gov, 2017). Retrieved 27 October 2020, from https://www.justice.gov/archives/ag/advancing-justice-through-dna-technology-using-dna-solve-crimes.
"Biological Evidence". Ncfs.Ucf.Edu, 2020, https://ncfs.ucf.edu/research/biological-evidence/. Accessed 27 Oct 2020.
Butler, J. M. (2015). The future of forensic DNA analysis. Philosophical transactions of the royal society B: biological sciences, 370(1674), 20140252.
DNA Exonerations in the United States. innocenceproject.org. (2020). Retrieved 27 October 2020, from https://www.innocenceproject.org/dna-exonerations-in-the-united-states/.
Farley, M. A. (2019). Forensic DNA technology. CRC Press.
Hampikian, G., West, E., & Akselrod, O. (2011). The genetics of innocence: Analysis of 194 US DNA exonerations. Annual Review of Genomics and Human Genetics, 12, 97-120.
LaPorte, Gerald M. (2017). "Wrongful Convictions And DNA Exonerations: Understanding The Role Of Forensic Science". National Institute Of Justice, https://nij.ojp.gov/topics/articles/wrongful-convictions-and-dna-exonerations-understanding-role-forensic-science#:~:text=According%20to%20the%20Innocence%20Project,as%20of%20July%2031%2C%202016.
Magalhães, T., Dinis-Oliveira, R. J., Silva, B., Corte-Real, F., & Nuno Vieira, D. (2015). Biological evidence management for DNA analysis in cases of sexual assault. The Scientific World Journal, 2015.
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Śpibida, Marta, et al. "Modified DNA polymerases for PCR troubleshooting." Journal of applied genetics 58.1 (2017): 133-142.
Turman, K. M. (2001). Understanding DNA evidence: A guide for victim service providers. https://www.ncjrs.gov/pdffiles1/nij/bc000657.pdf.
Vijay, P., & Singhal, P. S. P. R. (2015). DNA Technology: The Technology of Justice. Chief Patron National Advisory Board, 8. http://ietalwar.com/pdf/ijita.pdf#page=17
