DNA and Biological Evidence

Topic: DNA and Biological Evidence

Research Question:

Should DNA And Other Biological Evidence Be Admissible in Court?

Part A: Thesis Statement

Thesis Statement:

While DNA has been used to exonerate innocent people, many still hold that it should not be admissible in court because the quality of evidence relies on the quality of the laboratory work, evidence may be planted, and it might lead to false conclusions, and therefore should not be oversold in court and should only be considered in light of other available evidence.

Part B: Locating Sources

Source 1:

Campbell, R., Feeney, H., Goodman-Williams, R., Sharma, D. B., & Pierce, S. J. (2020). Connecting the dots: Identifying suspected serial sexual offenders through forensic DNA evidence. Psychology of Violence, 10(3), 255.

Abstract:

Introduction: Most sexual assaults that are reported to the criminal justice system will not be prosecuted. Researchers and policymakers have expressed concern that this long-standing practice allows offenders to commit additional sexual assaults. Determining whether reported sex offenders commit other sexual assaults requires establishing reliable linkages between two (or more) cases. Typically, criminal history records are used to identify repeat sexual offenders, but biological evidence in sexual assault kits (SAKs; also termed rape kits) provides another way to study how often reported sexual offenders commit additional sexual assaults by linking DNA across multiple cases to the same perpetrator.

Method: This study examined the forensic DNA testing results from a large sample of SAKs from Detroit, Michigan (N = 7,287). We assessed how many SAKs yielded a DNA match to a reference sample in the federal criminal database CODIS (Combined DNA Index System). We then ascertained whether the matching case was related to another sexual assault incident documented by state criminal history records.

Results: Approximately one third (35.7%) of the unique perpetrators in this sample had two or more sexual assaults linked via DNA, which is higher than what is typically documented in recidivism studies using court records (8–15%). Three case studies are presented that highlight how forensic DNA evidence can link multiple sexual assaults to the same perpetrator.

Conclusion: Forensic DNA testing of SAKs reveals a more complete picture of the scope of offenders’ sexual perpetration behaviors than what is documented in criminal history records alone.

How I will use this source in my research:

The source highlights the significance of DNA evidence, which include identifying the culprit of a crime. In this case, the study has been used to analyze past DNA samples in sexual assault cases in order to identify repeat offenders. The results of the study indicated that 35.7% had been involved in two or more sexual assault cases. The source will therefore be of great significance as it highlights the positive aspects of DNA and biological evidence in determining the guilt of a culprit. In this case, it can be used to analyze whether the suspect have been involved in other similar cases.

Source 2:

Rasool, N., & Hussain, W. (2020). ForeStatistics: A windows-based feature-rich software program for performing statistics in forensic DNA analysis, paternity and relationship testing. Forensic science international, 307, 110142.

Abstract:

Forensic science is one of the most modern and applied fields of science, today and comprises of various domains. These include Fingerprints analysis, Questioned document analysis, Forensic DNA and serology, Anthropometry, Cyber and Digital forensics, and many other fields. All these fields aid the process of decision making in the courts of law and legal settings; however, DNA profiling and its analyses are one of the most important aspects of forensic science today. In Forensic DNA analysis, the statistical calculations are very important to estimate the conclusiveness of DNA evidence in forensic cases; and to establish paternity and relatedness in civil and criminal matters. These statistics, when performed manually, leave a chance of error or ambiguity in the calculation, and are hectic and time-taking. Therefore, the computer-aided approaches are opted in forensics to perform DNA statistics calculations. Keeping its importance in mind, a highly accurate windows-based software program namely ForeStatistics is proposed in this study. ForeStatistics is rich in features such as DNA statistical calculations, DNA profile management and its matching. The software can estimate random match probabilities for single-source profiles, combined probability of inclusion for mixed profiles, paternity index of a disputed child in duo and trio cases, paternity of the disputed child when the alleged father is related to mother or biological father and relatedness in cases of grandparents/grandchild, avuncular relation and cousin. It is validated through different protocols and the validation of ForeStatistics depicts that it is highly accurate in terms of performing DNA statistics or DNA profile matching. Thus, it is concluded, that ForeStatistics has a great utility in the field of Forensic DNA analysis and can help DNA scientists, in performing various DNA related statistics, accurately and very efficiently.

How I will use this source in my research:

The source describes the technical advancement of forensic science including fingerprint analysis, foresnsic DNA and serology, questioned document analysis, cyber and digital forensics, and anthropometry. The source highlights the significance of DNA profiling as the most important aspect of forensic science today as it has been used to establish paternity, and relatedness in civil and criminal matters. The source will be of great help in my research as it uses ForeStatistics, a software program that is used in DNA statistical calculations, profile management and matching. The source does not only indicate the technical advancement in DNA profiling, but also indicates how the use of crime science has impacted how criminal investigations are conducted.

Source 3:

Schklar, J. (2019). DNA Evidence in the courtroom: A social-psychological perspective. In Science in Court (pp. 110-124). Routledge.

Abstract:

DNA profding and other kinds of scientific evidence are playing an increasingly important role in criminal investigations and court proceedings. When a trial involves DNA evidence, jurors are generally presented with testimony about the way in which the crime scene DNA evidence was collected and how the crime lab processed the evidence and tested for any matches between the various crime scene and comparison samples. A major approach studying lay reactions to probabilistic DNA evidence used Bayes’s theorem to estimate the degree to which jurors should revise their belief that the defendant committed the crime given some incriminating trace evidence such as blood, semen or hair fibre. Jurors’ background and experiences can affect their opinion as to whether they consider an inclusionary DNA match report to be incriminating evidence. Jurors may also have expectancies about the trustworthiness of police officers who conduct criminal investigations and criminalists who collect DNA samples from the crime scene.

How I will use this source in my research:

Based on my thesis, DNA and biological evidences should be used alongside other evidence in court and should not solely be used to determine whether an individual is guilty or not. The source will be or great help in my research as it cautions jurors to also question the trustworthiness of the police officers who conducted criminal investigations and criminalists who collected DNA samples from the crime scene especially when biological evidence such as semen, blood or hair fiber is found.