Chapter 3

The Contamination and Misuse of DNA

Vanessa Toncic, Alexandra Silva

"Genes are like the story, and DNA is the language that the story is written in." (Kean, 2012)

To understand how potentially mishandled or contaminated DNA evidence could be manipulated or presented in court, (under false pretenses), as an evidentiary ‘gold standard,’ it is important to first explain why, and under what circumstances, DNA evidence is in fact a gold standard. DNA evidence may be disguised as a gold standard when either the techniques used, or the representation of the data has been skewed and is no longer reflective of DNA as a gold standard. This chapter will explore the use of mixed DNA profiles as well as low copy number (LCN) techniques of DNA analysis, and how these methods may not be deserving of the ‘gold standard’ seal associated with DNA evidence. We will explore the biological aspect of issues with these methods and how they may reflect a contaminated DNA sample. Notably, DNA evidence that has been appropriately collected and analyzed may still be purposely misrepresented to a judge and/or . DNA as an evidentiary gold standard requires proper handling from the onset of collection, throughout analysis and storage, as well as during presentation in court to ensure that the quality of evidence is upheld. DNA evidence and its associated challenges are multi-faceted areas of study. These studies include issues surrounding the collection as well as the analysis of evidence leading to subsequent contamination and root cause analysis. There also exists debate on the ethics and privatization of DNA given the popularization of online DNA databases. The longstanding use of DNA evidence has also led to the propensity for DNA to potentially overshadow other scientific evidence in a forensic context, and for it to hold considerable weight in a judicial

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Are We There Yet? The Golden Standards of context. The following chapters will explore these topics and will also consider the future of DNA analysis.

DNA as an Evidentiary Gold Standard

The impact of DNA should not be understated. DNA analysis is a scientific advancement that can potentially demonstrate factual aspects of an event when used correctly. It is for this same reason that this type of evidence must be used appropriately, as there is great potential to abuse and misuse DNA evidence. DNA was regarded as the ‘gold standard’ of forensic evidence following the 2009 National Academy of Science (NAS) report. It was in this report that it was stated, “[w]ith the exception of nuclear DNA analysis…no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source” (NAS, 2009, p. 7). This made clear to the international forensic science community that no other evidence type had the capability of being as definitively individualizing as DNA evidence.

Gold Plated

Issues arise when methods of DNA analysis that are known to be less widely accepted are employed and subsequently presented as an infallible fact of science. In these cases, the DNA evidence is simply gold plated. What appears to be a perfect exterior of unflawed evidence can easily be distinguished as less than satisfactory under further inspection. Specific areas of DNA analysis such as mixed DNA samples and low copy number analysis are methods in which there exists room for error, moreso than in other techniques (Buckleton, 2009; Gill et al., 2006). These techniques are subject to increased bias on behalf of those who analyze and interpret such evidence. DNA samples that are contaminated by multiple DNA profiles or other biological and/or non-biological sources are not reflective of the same level of ‘purity’ as the gold standard of DNA evidence that we have come to know.

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DNA Mixtures

DNA mixtures, or mixed DNA profiles, are samples in which the DNA of two or more contributors are present (Hu et al., 2014). DNA mixture analysis presents a challenge to scientists as the ability to discern individual profiles become more challenging as the number of contributors increases (Hu et al., 2014). A more basic type of mixture contains a known source of DNA from a victim, and an unknown source from a suspect (Hu et al., 2014). The issues of reliability and accuracy in terms of identification of a suspect within a DNA mixture are primarily due to allele drop-in, allele drop-out, and stutter peaks (Hu et al., 2014). Gill and colleagues define allele drop-in as “contamination from a source unassociated with the stain manifested as one or two alleles,” where an allele describes the specific variation or trait encoded by a gene (2006, p. 101). In contrast, allele drop-out is a “low level of DNA insufficiently amplified to give a detectable signal” (Gill et al., 2006, p. 101). The difficulty of determining the number and identity of major or minor contributors in a DNA mixture is due to the possibility that the aforementioned factors can both mask allelic contributions as well as over-amplify alleles at various loci, or positions of a gene on a chromosome, in a random manner (Gill et al., 2006). This leads to distortion of the appeared number of contributors at each locus and makes it increasingly difficult to identify the various genotypes at said loci (Gill et al., 2006). Like with any physical evidence, mishandling and contamination are possibilities. In the case of DNA mixtures where multiple DNA profiles are already present in the sample, it is challenging to distinguish allelic drop-in from an additional DNA contributor. The addition of DNA in a sample after it is collected may occur at various instances including during collection or laboratory contamination. It is crucial to distinguish allelic drop-in from a DNA contributor in order for accurate crime-related identifications to be made (Hu et al., 2014). Similar to allelic drop-in, stutter peaks are a potential cause of misidentification in a DNA mixture (Gill et al., 2006). In the case of a DNA mixture that contains both major and minor contributors, a stutter peak of a major allele may be misidentified as a minor allele (Gill et al., 2006). A stutter peak occurs due to slippage of an enzyme during the process of amplifying DNA. It is often considered to be background noise (Gill et al., 2006).

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Biedermann and colleagues suggest that “the true number of contributors to a given sample cannot – in view of the currently used STR polymorphisms – be known with certainty” (2012, p. 689). In light of the many criticisms of DNA mixture analysis, the blanket statement that DNA is the gold standard of forensic evidence must be more critically viewed. DNA mixtures allow for greater bias and contamination as compared to a ‘pure’ DNA sample from a single contributor. This is something that a layperson, such as a jury member, is not likely to be aware of. This could impact one’s consideration of the evidentiary value of such evidence.

Low Copy Number Profiling

By definition, a low copy number (LCN) sample is that which has fewer than two hundred picograms of DNA present, and subsequently fails to meet the stochastic threshold (Budowle et al., 2009). The stochastic threshold allows scientists to be confident that the peak that they are interpreting is reliable enough to be used in their DNA analysis (Budowle et al., 2009). A low copy number sample is inherently ambiguous in nature and more prone to stochastic behavior, meaning it is also not reproducible (Budowle et al., 2009). Reproducibility is a condition one would think is necessary to be classified as a gold standard. When working with LCN samples, increased sensitivity testing may be required to compensate for the reduced concentration of DNA present in the sample (Buckleton, 2009). The caveat to increased sensitivity testing is the possibility of gross contamination or allelic drop-in as previously mentioned (see DNA Mixtures) (Buckleton, 2009). Contamination of a sample that occurs after collection or as the result of a sample mix-up is problematic and is another instance where DNA fails as a gold standard. Gross contamination occurs when a substantial DNA profile is extracted from the sample being analyzed due to contamination (Buckleton, 2009). It is possible that the sample could be contaminated with a suspect’s DNA profile. This could result in a as the individual may have had no involvement in the crime, yet the evidence would suggest otherwise. This contamination may also occur from a member of the police, a forensic professional involved in the case, or another individual unrelated to the crime. Increased sensitivity of DNA analysis is greatly susceptible to pre-submission contamination (i.e., the matter in which a sample was handled prior to being submitted to a forensic laboratory) (Buckleton, 2009). The lack of reproducibility of LCN samples in addition to the increased possibility of contamination of the sample must be

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The Contamination and Misuse of DNA Evidence considered when DNA evidence is broadly labelled as a gold standard of forensic science. Without sufficient training in the natural sciences, it can be difficult to fully comprehend methods used in various forensic science subdisciplines. This may result in the inability to assess the reliability of DNA evidence that is offered in trial. This is a necessary step on behalf of the judge and/or jury in order to ensure a fair trial. Issues may also arise if a forensic professional is not abundantly clear regarding the difficulties associated with analyzing and interpreting DNA mixtures and LCN samples when testifying in court or compiling a report. In this instance, a layperson such as a jury member may not be aware of the inherent difficulty associated with allelic drop-in or drop-out, stutter peaks, masking, and low copy number samples. These are factors that can bias the analysis of a sample and are essential to determining the weight in which DNA evidence should be afforded. The applications of DNA evidence in the criminal justice system are constantly evolving as new methods of analysis, equipment, and databases are developed. This poses challenges for the validation of these methods to ensure standardized processes, but it also provides hope that the evidentiary material presented will be of the highest possible quality. This will ensure that the integrity of the justice system is upheld, and no person is wrongfully convicted on the basis of false, misleading, or improperly handled DNA evidence (see Chapter 2 for case studies). New developments and findings of misuse of DNA evidence have the

INNOCENCE CANADA

Innocence Canada is a non-profit organization that was founded in 1993. The organization has contributed to the exoneration of 23 individuals in Canada since (Innocence Canada, n.d.). There are many instances in which the use of DNA evidence has contributed to the wrongful convictions as well as the subsequent exoneration of these individuals. The exonerations of Kyle Unger and James Driskell (see Chapter 2) are notable cases where Innocence Canada assisted in identifying microscopic hair analysis evidence which was used to wrongfully convict each individual (Innocence Canada, n.d.). Advancements in DNA technology were subsequently used to overturn both wrongful convictions (Innocence Canada, n.d.).

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Are We There Yet? The Golden Standards of Forensic Science potential to be retroactively used to exonerate those who have been wrongfully convicted due to DNA evidence that did not adhere to the gold standard set forth.

Issues Can Arise at Any Time

DNA contamination, as well as the transfer of DNA, can undoubtedly occur in various instances. When exogenous DNA, DNA from an external source, is mixed with DNA relevant to a particular case, it produces DNA contamination or mixture. Similarly, contamination can occur through transfer. Primary DNA transfer occurs when DNA is transferred from one person to another person or object (i.e., Person A touches a handgun with blood, and the blood is now transferred to Person A). A secondary transfer occurs when the DNA is transferred from the primary person, onto another intermediate, and then onto another person or object (i.e., the bloody handgun is touched by Person B who then touches Person A, thereby transferring the blood from the handgun onto Person A) (Taylor et al., 2016). DNA is considered the gold standard of forensic science, but in many cases, DNA evidence fails. Now that this background has been established, the various instances where these transfer or contamination issues are seen throughout criminal investigations can be further analyzed. When these issues do arise, the results of DNA analysis are impacted and may potentially be entered into court, which can affect the case. This can lead to a very thorough investigation and analysis to determine the root of the issue – however, the court may accept the evidence and not think about the issues caused. Additionally, there has been uncertainty with DNA analysis over the years due to concerns such as police training and laboratory quality assurance. Studies have indicated that DNA can easily be altered at any point yet still be used during an investigation. Miscarriages of justice are always occurring or being reviewed especially by Innocence Canada, for example, that have 90 cases currently open (Innocence Canada, n.d.). Thus, there must be preventative action taken to determine the ‘why’ for all the contamination concerns observed. Taking a root cause analysis approach will give investigators a better understanding of the process to determine why these issues occur and will examine some preventative steps that can be taken. In an investigation, the collection of evidence is the first step, and also a key place where contamination or transfer can occur. We see multiple opportunities in the laboratory for contamination as well as mixed DNA samples (van Oorschot et al., 2010). In order to express the importance

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The Contamination and Misuse of DNA Evidence of DNA, these issues need to be reduced and prevented when possible, to ensure DNA is held to the gold standard.

DNA Contamination and Transfers

DNA has been the gold standard for quite some time now – given this, one may wonder why and how DNA evidence is constantly misused. At a crime scene, DNA may be found, collected, and brought to the lab for further analysis. This analysis can result in an identification, a non-identification, or be inconclusive. Even with an identification, however, the DNA may have been exposed to other factors that would cause contamination. It is therefore never fully known when or how DNA such as hair, or blood, got into the crime scene (Fonnelop et al., 2016). It is also noted by Fonnelop and colleagues (2016) that as more techniques develop and become more precise, it is important to keep in mind that the probability of developing a DNA profile from a sample that identifies the examiner is increasing. Nonetheless, the criminal justice system continues to be presented with DNA evidence that has been contaminated and still fails to take the issue more seriously. Miscarriages of justice are occurring more than ever and may be the result of a disorganized collection of evidence (Gill, 2018). This disorganized collection of evidence may be due to underfunding at various police departments, which can come in the form of unfit police officers and other personnel at a scene, who may be under or improperly trained. To minimize contamination, many studies and publications, including the 2009 NAS report and the 2012 Hart House Report, recommend not only the use of best practices, but also the continuous education and training for individuals involved in the developing field of forensic science, specifically in forensic biology. These reports presented recommendations that are to be applied in the field and labs as well as indicates that the use of best practices needs to be increasingly implemented in order for forensic science to be effective in the criminal justice system.

Where do things go wrong?

Both contamination and transfer issues of DNA can occur at any stage during an investigation. At the crime scene, there are countless opportunities for hairs or fibers to be left behind by either a police officer or by other individuals on the scene. According to Schiro (2007), the collection and handling of evidence are

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Are We There Yet? The Golden Standards of Forensic Science where the first signs of DNA misuse or contamination occurs. As discussed later in this chapter, most issues can be narrowed down to the root of the cause – which can be the handling and collection of evidence. The police have the duty to collect and handle evidence until it is brought to the lab or a secured location for analysis. Failure to sufficiently perform this duty has led to miscarriages of justice. As the first responders to a scene, police have a job to either ensure it is secured and wait for proper investigators to arrive, or to properly collect, handle and preserve evidence (Schiro, 2007). Unfortunately, there are times when neither the former nor the latter occur. In some cases – like the OJ Simpson case – the police have the tendency to leave their own footprints and DNA at the scene, thereby contaminating areas that would need to have been secured (Lee & Ladd, 2001). Although this may not be the case in every situation, it is still the case in some. Regardless of whether the concern is attributable to the officers not being properly qualified or the officers not wearing proper protective equipment, the issues continue to arise. Once collected, evidence is brought to the lab for further analysis by forensic scientists, who also must follow guidelines to avoid similar issues. A study done in 2016 by Taylor and colleagues aimed to find ways to remove DNA found on hard surfaces like lab benches. Their goal was to determine if certain cleaning substances would remove DNA from these surfaces, in turn helping to prevent DNA contamination (Taylor et al., 2016). To do this, Taylor et al., (2016) looked at the difference in DNA amplification based on how long it was left on a particular surface. Their conclusion stressed that surfaces must be properly cleaned, and precautions must be taken prior to analysis to ensure no DNA remains on lab surfaces (Taylor et al., 2016). Surfaces, however, are not the only way that contamination can occur. The gloves a scientist wears are another key source of DNA transfer. If a scientist wears gloves to analyze DNA at one bench, then moves locations without changing gloves, a secondary transfer is bound to occur (Fonnelop et al., 2015). Sadly, this can lead to a series of events resulting in the contamination of multiple benches, and potentially multiple pieces of evidence. A study done by Gorey et al., (2019) investigated the issue of loss of DNA due to transfer via gloves. Gloves were swabbed to test for DNA, and the frequency that they were changed was recorded. The researchers used mock casework to generate profiles that could be used for comparison against the staff members (Gorey et al., 2019). The generated profiles were identified as either staff members or the suspect. Not only was the suspect's DNA found on the gloves, but staff members' DNA was also found to a significant enough degree such that it was able to be used to generate

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The Contamination and Misuse of DNA Evidence a profile (Gorey et al., 2019). This indicates that a contamination event had occurred, thereby altering the results of the profiles and affecting the evidence. If this was a case that was brought to court, there would be a line of questioning around how staff members' DNA generated a profile, as well as a questioning of the laboratory’s protocols. This is an issue because once admitted into the court, contaminated evidence can cause a case to be thrown away but also potentially convict the innocent. This is a situation that is seen all too often and needs to be prevented.

Root Cause Analysis

Root Cause Analysis (RCA) is a systematic technique that has been developed to ask the five ‘why’s’ to identify the root of an issue (Williams, 2001). The goal is to isolate what, how and why it happened, and when it occurred. DNA contamination can occur so easily that one transfer can lead to another, creating a chain of reactions, thereby creating a bigger issue that could affect more than one sample. RCA can allow one to understand the connection of all the issues and allow for backtracking to determine where these issues occurred (Rooney & Heuvel, 2004). Undergoing RCA includes identifying the issue, collecting data, recognizing any factors that could be causing the issue, acknowledging the root of the issue, and recommending preventative steps to reduce or prevent this issue from occurring in the future (Williams, 2001). Although the RCA technique can be used in any field, this section will specifically be focusing on RCA in relation to the misuse of DNA contamination and transfer. Forensic laboratories are one place where DNA as a gold standard can be misused. According to the National Commission on Forensic Science (2017), there are requirements that accredited forensic laboratories must follow when procedures are put in place, as well as their preventive and corrective actions. This commission explains that RCA must be completed prior to any corrective action being put in place. This RCA step is crucial, and when undertaking it, it is important to avoid any biases or tunnel vision. RCA is designed to specifically target the main cause in any issue and those at fault could include law enforcement, fellow lab members, or other individuals. Once the issue is established, there actions that can be put into place. Corrective actions differ from preventative actions because they aim to respond to the issue or event that occurred. On the other hand, preventative actions aim to stop the issues from reoccurring in the future (Houck, 2016).

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Contamination, mixed samples, or the transfer of DNA can all be traced back to one instance or instances. In some cases, the handling and collection of evidence done by police officers is where the mishandling takes place. DNA is a biological sample that is very sensitive and crucial to an investigation, and therefore must be handled properly to be sufficiently extracted and analyzed. DNA evidence should not be moved or altered to preserve it in its original form. That being said, there have been investigations where officers did not follow proper protocol, moved evidence, and/or contaminated the DNA on the scene—the OJ Simpson case is a notorious example of this (Lee & Ladd, 2001). In cases similar to this when police officers or other personnel come in contact with DNA, a contamination event is created, and an RCA is completed. Corrective and preventative actions can be put in place to minimize this contamination from occurring. A common yet effective preventative action is continuous training and education for individuals involved in forensic cases (Lee & Pagliaro, 2013). A recommendation by the NAS report in 2009 emphasizes the importance of these training protocols. Training on evidence handling and the preservation of evidence – specifically DNA – is a vital skill to have due to its impact on any case (Lee & Pagliaro, 2013). Hauhart & Menius (2014) conducted a literature review and discussed studies that revealed majority of officers felt ‘dissatisfied’ with the training in DNA evidence available to them as well as the funding available for the DNA unit. This suggests that for DNA evidence to continue to be held as the ‘gold standard,’ there needs to be more training, procedures, and strict guidelines in place.

Final Words

Throughout this chapter, it has been clear that DNA is a biological sample that can be easily contaminated, altered or tampered with, even though it is held as the gold standard. This misuse can be incredibly impactful on any case and can potentially destroy a criminal investigation. DNA mixtures and LCN samples in laboratory analyses are why we see a failure in the gold standard. DNA evidence is gold plated in cases where the methods that are less widely used are presented in court as reliable. To prevent these issues from occurring, root cause analysis is a technique that should be applied to identify where things go wrong and why these issues arise. As technologies advance and the field of forensic science continues to develop, it becomes more crucial for DNA evidence to be analyzed without any contamination if the court wants to avoid a possible wrongful conviction. Through listening to

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recommendations from reports and expanding our knowledge to understand why wrongful convictions occur, we must move forward with further education in the area of DNA to maintain the gold standard.

References

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Debus-Sherrill, S., & Field, M. B. (2019). Goray, M., Pirie, E., & van Oorschot, R. A. H. Familial DNA searching-an emerging (2019). DNA transfer: DNA acquired by forensic investigative tool. Science & Justice, gloves during casework examinations. 59(1), 20-28. Forensic Science International: Genetics, 38, https://doi.org/10.1016/j.scijus.2018.07.006 167–174. https://doi.org/10.1016/j.fsigen.2018.10.018 Dror, I. E., & Hampikian, G. (2011). Subjectivity and bias in forensic DNA mixture Hauhart, R. C., & Menius, K. R. (2014). DNA interpretation. Science & Justice, 51(4), 204- evidence: Examining police officers’ 208. knowledge of handling procedures in a mid- https://doi.org/10.1016/j.scijus.2011.08.004 size department. International Journal of

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