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The purpose of this essay is to examine the credibility and validity of forensic hair morphology. This study examines the morphological physical characteristics of human hair. Microscopical hair analysis only compares class characteristics and does not obtain any genetic information linked to an individual. In recent years there has been increasing controversy over the admissibility and reliability of hair comparison evidence used in courtrooms. Specifically, microscopic human hair analysis before the use of DNA profiling. Since the introduction of DNA analysis, forensic investigators focus their attention on evidence that can be narrowed to one individual using nuclear or mitochondrial DNA. Due to the flawed methodology many people were wrongfully convicted for crimes they did not commit, since the discovery of this flaw many rules were put in place to make sure wrongful convictions were not committed in the criminal justice system.
Hair morphology is not currently used as evidence alone in court, although it can be utilized alongside DNA testing to solidify the evidence. Forensic hair examination is a comparative discipline that works with microscopy, biology, anatomy, and histology. The characteristics of human hair are assessed by observing the anatomy of the hair, which then reveals categories like race and disease. Other factors, such as the forced removal of hair at a crime scene, can be a useful tool for the investigation to prove that a crime has been committed. To be foundationally valid, a field must utilize a method thats been tested countless times by multiple people and prove to be repeatable and reproducible. Scientists must compare their findings of the morphological features found in hair, which include length, scales, color, and medullar patterns. Scientists compare the results numerous times to solidify conclusions. This is particularly important when it comes to hair comparisons because of the bias that a person can portray knowing the evidence and details of a crime scene. There have been many debates that discuss the validity of hair comparison in crimes, particularly the discrimination between the suspect and a hair found at the scene. Many hairs share similar alleles and characteristics, which may result in bias by the examiner. For years the courts accepted that hair comparisons as reliable and valid in court. However, the Daubert ruling was later introduced to the courtroom to consider if the methodology used is scientifically acceptable and valid, an expert could not testify about the certainty of the technique used unless it proved to be accurate and the rate error is unknown, which applies to hair morphology and the bias judgments that follow. The concept of error rates is essential to court cases due to human errors like mishandling samples or contaminations that contribute to wrongful convictions. Wrongful convictions obligated judges to thoroughly look over the evidence and base their case only on scientifically valid reasoning, not opinions. Hair morphology is not valid in the forensic and scientific community and is becoming less appropriate in courtrooms due to newer forensic tests. Moreover, forensic science can fail in a few ways, such as the fact that it lacks reliability and the inability to reproduce valid results, and incompetence.
The relevance of hair morphology is declining in popularity, essentially becoming a dying art due to its lack of DNA. The Innocence Project, which exonerates the wrongfully convicted, has freed hundreds of innocent people due to the error in microscopical hair comparisons. Due to the fact that the hair comparisons were deemed reliable in innocent peoples cases, the forensic investigators were affected by tunnel vision. Tunnel vision is a great flaw in the criminal justice system, where they focus on a suspect and select and filter the evidence that will build a case for conviction while tuning out and ignoring evidence that points away from the guilt. There has been a devaluation of microscopic human hair analysis since DNA profiling, which matches the genetic makeup of one particular individual from the root of the hair. There is a decline in this practice and is rarely used as incriminating evidence on its own. Hair microscopy was the second most popular type of testimony used in court, yet half of the cases involved improper statistics because the testimony was comparing common characteristics with reference hairs collected from a defendant or victim. In a recent FBI article, there were comparisons made between microscopic and mitochondrial DNA hair comparisons and found that 1 in 11% of the cases revealed that the hairs that were deemed similar but were not a match through DNA. 158 people were exonerated in the United States using post-conviction DNA evidence that proved their innocence after years of wrongful conviction. There are a lot of limitations when it comes to hair comparisons because hair cannot be uniquely identified by one person.
DNA has revolutionized criminal investigations by becoming faster and easier to obtain. Hair is one of the most frequent types of evidence found at a crime scene, which is easy to obtain, especially where a violent struggle has occurred. Forensic scientists then focus their attention on the DNA of the root of the hair that can be extracted and linked to the perpetrator. The reason hair comparison methods are outdated is because of the birth of DNA. There are three types of DNA. The first type is male-linked Y-chromosomes that are directly passed from father to son. Autosomal DNA tests all the chromosomes, and the third type is mitochondrial DNA, where a mother passes her genes to her daughter. Nuclear DNA cannot be isolated from a hair shaft, making it impossible to search for DNA, but if a hair is still attached to the root, then it can be extracted and examined by keratinocyte cells, which can provide genetic information about an individual. DNA is short sequences that are repeated numerous times and vary from each individual. DNA is found in most cells of the body, such as a persons saliva perspiration or epithelial cells, to extract the DNA chemicals are added to break open the cells and isolate the DNA from other components. Genetic identification and profiling are only possible through DNA analysis. Another efficient scientific technique is mitochondrial DNA, which is mentioned earlier and is more abundant than nuclear DNA. A typical human cell has thousands of copies of mitochondrial DNA as opposed to one single copy of nuclear DNA. Each individual is very unique, but genetically humans share a lot of similarities. The region that differs people is a region of DNA strands called polymorphisms. Each human inherits a unique combination from their blood parents. This technique has a very high success rate because individuals sharing a common maternal bloodline share the exact same mitochondrial DNA. The early life of DNA analysis did not work unless physically given the suspect and their blood, which is extremely unlikely to happen. The criminal justice system should ensure that its DNA sample is valid, reliable, and tested multiple times, and always supports the final conclusion. The introduction of this new technology impacted society and the forensic field for the better. Another amazing factor of DNA is that there is a global database that holds information on known offenders that can be transferred from one team to another. INTERPOL holds fingerprints, facial images, and DNA that is easily accessible.
Hair comparison was used as early as 1934 when microscopic hair comparison was used in a murder trial. The forensic team visually compared a hair at the scene to the accused. This was then commonly used by laboratory personnel as part of their investigations. Since the birth of DNA, hair analysis is no longer available in courtrooms. As mentioned earlier, hair comparison can only be used in court if it is present with DNA analysis.
Microscopic hair comparison analysis is a flawed forensic technique that does not pass the Daubert ruling and cannot be presented in a courtroom. In contrast to hair morphology, nuclear and mitochondrial DNA testing is the most effective way of identifying individuals based on trace evidence left at a crime scene. Unlike hair analysis, DNA is individually fixed and unique. DNA is replicable, valid, relevant, and has international large databases. The Innocence Project proves that this flawed system has convicted innocent people of heinous crimes due to hair comparisons. These people were later exonerated by DNA analysis, a new recent reliable source. Forensic hair morphology proved to be seriously outdated by newer forensic technologies that are more sophisticated as well as not containing a concept of error rates due to inefficient results that can be replicated and reproduced. There is a decline in this practice and is rarely used as incriminating evidence on its own. The way to see hair microscopy used is when presented with DNA. Hair microscopy was the second most popular type of testimony used in court, yet half of the cases involved improper statistics due to the fact that the testimony was comparing common characteristics with reference hairs collected from a defendant or victim. There are a lot of limitations when it comes to hair comparisons because hair cannot be uniquely identified by one person just by the hair shaft alone. Thanks to this discovery online databases have been created to quickly and efficiently shift through millions of samples to match the DNA to the perpetrator and give the victim the justice they deserve.
References
- Friedman, J., Brand, J. It Is Now Up to the Courts: Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods. Santa Clara Law Review, 57, no. 2 (2017): 367-384
- Hampikian, G., West, E., and Akselrod, O. (2011). The Genetics of Innocence: Analysis of 194 U.S. DNA Exonerations. Annual Review of Genomics and Human Genetics, 12: 97-120.
- Houck, M., and Budowle, B. Correlation of Microscopic and Mitochondrial DNA Hair Comparisons. Journal of Forensic Sciences, 47, no. 5 (2002): 1-4.
- Saks, M. J., Risinger, D. M., Rosenthal, H., Thompson, W. C. Context Effects in Forensic Science: A Review and Application of the Science of Science to Crime Laboratory Practices in the United States. Science & Justice, 77-90 (2003).
- Smith, S. L., Linch, C. A. A Review of Major Factors Contributing to Errors in Human Hair Association by Microscopy. The American Journal of Forensic Medicine and Pathology. 1999; 20(3): 269-273.
- Taupin, J. M. Forensic Hair Morphology Comparison a Dying Art or Junk Science? Science and Justice 2004; 44(2): 95-100.
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