Deoxyribonucleic acid, or more commonly known as DNA, it is a carrier of genetic information, it is what gives specific characteristics or qualities to individuals that are unchangeable. It’s what makes us unique, and it’s what we leave behind whether it’s our saliva, our fingerprints, a strand of hair, sweat or mucus. Forensic investigators can take samples of these and use them to get the DNA out of them. Although DNA analysis has transformed forensic science, forensic scientists are concerned with how DNA can be used in criminal investigations and how it is misunderstood and misrepresented when it is used in court. When DNA evidence or any type of evidence is presented in a courtroom its purpose is to be as clear as possible in order to for the courtroom to make the right decision. But if the evidence is misunderstood by the jury or misrepresented to even the judge it can lead to the wrong decision.

DNA evidence is accurate science, it has been around for decades, and is well-studied, 99.9% of our DNA is shared to other individual’s genes but only 0.01% of our genes is what makes us different. Although it is a small percentage it is was makes us unique from everyone else and can make an impact in criminal trials.

In 2002 new technology was invented to analyze DNA that’s found in crime scenes. It transformed the forensic field, but there was a limit to what DNA could convey about a crime and what it can and cannot prove in court. DNA profiles, for example, are not specific enough to reliably identify an individual. A DNA sample would ideally be complete enough to examine the sixteen different markers (points in a fingerprint that can be drafted), but when the DNA of the sample damaged or incomplete (only some would be presented), meaning that it wouldn’t be possible to create a whole DNA profile but only partial. While the DNA sample may be complete the DNA profile that was created can match with an individual other than the criminal[1]

Fingerprint evidence has great value, the dependence on fingerprints relay on two principles: persistence and uniqueness. Fingerprint analysis goes through a process of Analysis, Comparison, Evaluation, and then Verification (the ACE- method). Analysis, involves the decision whether the latent fingerprint is sufficient in quality for a comparison to be made. If it is suitable then its minutiae, are then identified and logged. Comparison and Evaluation, when comparing the results of fingerprint evidence presented to participants, they discovered that most ’match’ decisions increased as the emotional information became more powerful, a clear effect of cognitive bias from the presence of contextual evidence. But it does not just affect students (participants) but experts as well, demonstrated by Dror and Charlton demonstration. Lastly, verification, during this stage a second person would analyze and verify the decision of an initial decision maker. This would be considered a quality control mechanism,[2] meaning it is the last check to determine whether the results are accurate and free of errors.

Evidence could possibly be misleading if its significance is not understood completely. As information and forensic research continues to grow, so do doubts, and the challenge to priorities research and evaluate the consequences and extent of misleading evidence in criminal cases remains. There was study that used a systemic content analysis to identify misleading evidence, it pulls information from transcripts of cases whose ruling argued unsafe by the Court of Appeal of England and Wales. During the 7 years the study was conducted, 218 applications were successfully appealed, in which contained 235 cases of misleading evidence. Out of the successful appeals the majority of them (76%) were based upon the same material that were available in the original trial, meaning no new information was presented in the appeal. All of the cases had common observed types of evidence; 39% (of 235 cases) were witness evidence (eyewitness testimonies, etc.), 32% was forensic evidence, and 19% was character evidence. But only 26% of witness evidence was valid, meaning either the person testimony was not used, or the person showed signs of unreliability. This is because 66% of misleading evidence types are related to the interpretation at an activity level this can lead to cognitive bias, when the performance of a task is affected by the task itself, the presence of context information can alter or affect the opinion that could be reached. They could have all been prevented by providing a more transparent connection between evidence and hypotheses.[3] Removing bias would just validate DNA evidence more and make it even more reliable than other more conventional kinds of evidence.

When conducting an investigation, DNA sequencing is a very powerful tool to identify individuals or to determine a specific ethnic and observable characteristic even if there’s heritable changes in cellular phenotype (observable characteristics). Over the course of ten years there has been noticeable epigenetic markers that can have forensic significance.  It is possible that there can be alterations in DNA methylation (addition of a methyl group) patterns that could aid many forensic investigations, such as differentiating monozygotic twins, identify tissue source or determining the age of tissue donors. But there are some limitations to this approach, such techniques can be combined with polymerase chain reaction (PCR), an amplification technique for cloning specific parts of a DNA sequence to make thousands to millions of DNA copies of interest, or any other similar based methods but there is caution due to the limitation of the amount of DNA it can create PCR bias.[4] Yet having a sample of DNA and being able to amplify the sample large enough to take what is needed to examine cellular phenotypes is still an advantage to DNA evidence. There be no need to amplify the sample to a point where it would create PCR bias nor have any errors and being inaccurate, like when analyzing fingerprints.

As mention before not only can DNA sequencing tell us an individual phenotype, but differential DNA methylation can also help find an individual on a cellular level as well, this would fall under forensic epigenetics. Differential DNA methylation has been useful for three forensic applications in specific, 1) determining the tissue type of the individual’s biological race, 2) estimating age, and 3) differentiating between monozygotic twins. Current methods in forensic epigenetic profiling such as, wide range in CpG (CpG-3′ methylation) markers and targeted DNA methylation analysis are popular methods. DNA methylation patterns are maintained during DNA replication by the addition of methylated groups to daughter strands by methyltransferases. Hence, when a candidate CpG marker is found it should undergo extensive validation to investigate stability and potential effects, like genotypic and phenotypic influences, such as; gender, tissue, age, and disease.[5] This would just also check that it is free of error, if it is noticed that the CpG marker is unstable and has potential effects it would not be used and as a result the process would begin again from the start. But before testing and analyzing DNA it is important to highlight the importance of DNA evidence handling, because any contamination of the evidence when collecting it would just give us inaccurate results.

When managing any type of forensic evidence, especially DNA evidence, it is crucial that it does not get contaminated because it effect the results of the evidence. The measure of the quality of DNA evidence is increasing scrutiny. There’s a need of improvement in the management of DNA evidence to prevent any bias interpretation of the evidence and to ensure the validity of the evidence as well. The Forensic Science Regulator in the United Kingdom, published a set of Codes of Practice and Conduct, in 2011, to ensure DNA evidence management and quality. The codes tell how to manage the evidence; however, it does not tell forensic investigators how to perform the investigation. Meaning they can carefully manage the evidence (not get it contaminated or ruined) and they can use it in a bias way to get the verdict to vote in their benefit, as long as the evidence was well handled and managed it is valid and can be used. The aim of the ISO standards is to reduce the probability of human and instrument error, which in some states (in the UK) don’t find crucial when managing evidence. Quality Assurance, QA, as defined in ISO is, “part of quality management focused on providing confidence that quality requirements will be fulfilled” It’s to prevent an error in the making of a product or service, since it’s meant to be in working conditions. Quality control is similar to quality assurance, is to make sure the results from the evidence is the same as what were expected, or how “correct” the results and evidence are.[6]

Taking in account all the challenges and limitations in DNA evidence, there’s more research to be done. There must be a bigger conversation of DNA evidence about its; management, quality, and validity, as well as its reproducibility, making sure there are multiple samples under optimized conditions to prevent any error. Court related, besides using the evidence in a bias way, a conversion of the digestion of DNA evidence, allowing the jury to fully understand the evidence to prevent any unbiased decisions, and finally, its applicability, testing commonly found forensic samples to establish any related effects making the evidence more valid.

 

 

 

[1] Elster, Naomi., How Forensic DNA Evidence Can Lead to Wrongful Convictions, JSTOR Daily, Dec. 2017

[2] Stevenage, Sarah V., Bennett, Alice., A Biased Opinion: Demonstration of Cognitive Bias on a Fingerprint Matching Task Through Knowledge of DNA Test Results, Forensic Science International, Vol. 276, (2017), pp. 93-106

[3] Smit, Nadine M., Morgan Ruth M., Lagnado, David A., A Systematic Analysis of Misleading Evidence in Unsafe Rulings in England and Wales, Science & Justice, Vol. 58, Issue 2, (2018), pp. 128-137

[4] Vidaki, Athina., Daniel, Barbara., Syndercombe Court, Denise., Forensic DNA Methylation Profiling-Potential Opportunities and Challenges, Forensic Science International: Genetics, Vol. 7, Issue 5, (2013), pp. 499-507

[5] Vidaki, Athina., Kayser, Manfred., Recent Progress, Methods and Perspectives in Forensic Epigenetics, Forensic Science International: Genetics, Vol. 37, (2018), pp. 180-195

[6] Page, Helen., Horsman, Graeme., Sarna, Anna., Foster, Julienne., A Review of Quality Procedures in the UK Forensic Sciences: What Can the Field of Digital Forensics Learn? Science & Justice, Sept. 2018