WAS CARL WEBB THE SOMERTON MAN? A DETAILED ANALYSIS OF THE DNA CASE AND AN UNPALATABLE TRUTH...

Imagine you're watching a true crime documentary. The investigators have found a crucial piece of evidence—a single strand of hair. They send it to the lab, hoping it will provide the answers they need to crack the case. But what exactly can a hair sample reveal? And how reliable is the information it provides, especially when it comes to complex forensic cases like the Somerton Man mystery?

To fully understand the power of hair in forensic science, we need to explore the differences between two types of hair samples: one that includes the root, and one that is just a rootless shaft. These differences have profound implications for what investigators can learn from these samples, and ultimately, how reliable their conclusions might be.

Hair Samples: Rooted vs. Rootless

When it comes to analyzing hair, the presence or absence of the root is crucial. A hair sample with its root intact contains nuclear DNA—the complete set of genetic material found in almost every cell of the body. This type of DNA is highly specific to an individual, providing a detailed genetic profile that can be used for identification, genealogical research, and even health assessments.

On the other hand, a rootless hair shaft only contains mitochondrial DNA (mtDNA). This type of DNA is found in the mitochondria, the energy-producing structures in cells, and it’s passed down exclusively from the mother. While mtDNA can provide useful information, it’s far less specific than nuclear DNA. Because mtDNA is shared among all maternal relatives, it can’t uniquely identify a person the way nuclear DNA can.

To illustrate the differences between these two types of DNA, let’s look at a simple chart that compares them:

Here's a comparison chart:

What This Means for Forensic Conclusions

These differences between nuclear and mitochondrial DNA are more than just scientific trivia—they have real-world implications for forensic investigations. Let’s break down how they can impact the outcome of a case.

1. Accuracy and Specificity:

• Nuclear DNA (from a hair root) is incredibly accurate and specific. It acts like a genetic fingerprint, providing a match that is unique to the individual. This makes it a powerful tool in criminal investigations, where pinpointing the exact person involved is crucial.
• Mitochondrial DNA (from a rootless shaft), while useful, is less definitive. It can include or exclude someone from a maternal lineage, but it can’t provide a unique identification. This means that in cases where only mtDNA is available, the conclusions drawn must be more cautious.

• The high specificity of nuclear DNA minimizes the risk of misinterpretation. If a match is found, investigators can be confident in their conclusions.
• With mtDNA, there’s a higher chance of ambiguity. For instance, if mtDNA links a suspect to a crime scene, it might also link their maternal relatives, potentially leading to confusion or false leads.

• Nuclear DNA evidence is gold standard in courtrooms. Its reliability makes it a cornerstone of many legal cases.
• Mitochondrial DNA, while admissible, carries less weight. Judges and juries are often advised to consider its limitations, particularly the fact that it cannot uniquely identify an individual.

• In cold cases, where evidence might be decades old, nuclear DNA can provide definitive answers and close cases that have remained unsolved for years.
• Mitochondrial DNA, though useful, might only help narrow down suspects to a maternal lineage, rather than providing the conclusive proof needed to solve the case.

The Role of DNA Imputation

DNA imputation is a technique that scientists use to fill in missing pieces of genetic data. It’s like using a puzzle’s reference image to guess where missing pieces should go. In large-scale genetic research, imputation is invaluable. It allows scientists to predict missing genotypes in a sample based on patterns found in a reference population.

However, when it comes to forensic science, particularly with hair samples, the role of imputation is limited. Since imputation relies on nuclear DNA, it can’t be applied to rootless hair shafts, which only contain mitochondrial DNA. Therefore, in cases where only a rootless hair shaft is available, like in the analysis of the Somerton Man’s hair, imputation doesn’t improve the results.

While imputation is incredibly reliable in the right context, such as large-scale studies where it can increase the power of genetic research, it isn’t typically used in forensic cases where the utmost accuracy and specificity are required. Forensic scientists prefer directly observed DNA sequences, especially in legal contexts where the stakes are high.

The Case of the Somerton Man

To bring this all together, consider the Somerton Man case. This mysterious unsolved case from 1948 has intrigued investigators and researchers for decades. In 2022 claims were made that Carl Webb was the Somerton Man, based on DNA extracted from a rootless hair shaft and supplemented by imputation techniques. However, given the limitations of mtDNA and the role of imputation, these conclusions must be viewed with caution.

The absence of nuclear DNA in the hair shaft means that the evidence is not as definitive as it might seem. While it’s possible to trace a maternal lineage using mtDNA, the unique identification of an individual, like Carl Webb, requires nuclear DNA. Without it, the claim remains speculative, highlighting the importance of understanding the science behind forensic evidence.

Complicating Factors: Embedding and Embalming

The situation becomes even more complex when considering additional factors like the condition of the hair sample over time. In this case, supposedly the rootless hair sample had been embedded in a sisal/plaster casing for 70-plus years and the body from which it came had been subjected to embalming. These factors would further complicate the use of DNA imputation:

1. Prolonged Embedding in Sisal/Plaster Casing:

• The hair sample's exposure to environmental factors such as temperature, humidity, and chemical interactions with sisal and plaster over that time would likely lead to significant DNA degradation. Even if mtDNA can be extracted, the DNA might be highly fragmented, reducing the quantity and quality of genetic information available for analysis.

• Chemical Challenges: Embalming involves the use of chemicals, particularly formaldehyde, which can severely impact DNA. Formaldehyde causes cross-linking of DNA strands, making the DNA more difficult to extract and analyze. Over time, this chemical treatment can lead to significant degradation, reducing the overall yield and quality of DNA available for forensic analysis.
• Fragmentation and Yield: The DNA recovered from embalmed bodies is often fragmented and available in much smaller quantities. This further complicates the use of imputation, as the degraded and cross-linked DNA might be insufficient for reliable imputation.
• Specialized Techniques Required: Recovering DNA from embalmed bodies requires advanced extraction techniques that can address the challenges posed by chemical cross-linking. While some mtDNA may still be recoverable, the overall process is more complex and less likely to yield a complete genetic profile.

Given these additional challenges, imputation would likely produce unreliable results, if any results at all. The degraded and chemically altered DNA would limit the effectiveness of imputation, making any forensic conclusions based on such an analysis highly uncertain.

Final Considerations: Lack of Transparency in Sample Retrieval

An important detail that further complicates the analysis is the lack of transparency regarding the rootless hair shaft used in the analysis. No clear information has been provided about where or when the hair sample was found, nor about the method used to retrieve it or the person who handled its collection.

This lack of documentation and transparency raises concerns about the chain of custody and the integrity of the sample. In forensic science, the chain of custody is crucial to ensure that the evidence has not been tampered with or contaminated. Without this critical information, the reliability of the DNA analysis is further compromised, casting additional doubt on the conclusion that Carl Webb was the Somerton Man.

Conclusion: The Power and Limits of DNA Evidence

DNA evidence is a powerful tool in forensic science, capable of solving cases and providing closure to mysteries. However, understanding the differences between nuclear and mitochondrial DNA, the role of techniques like imputation, and the impact of environmental factors and chemical treatments like embalming is crucial for accurately interpreting this evidence. In cases like the Somerton Man, where the available DNA is limited and potentially compromised, it’s important to recognize the limitations and proceed with caution.

Additionally, the lack of transparency regarding the retrieval and handling of the hair sample adds another layer of uncertainty, emphasizing the need for careful consideration before drawing any definitive conclusions. By understanding these concepts, we can better appreciate the complexities of forensic investigations and the science that drives them. Whether you’re watching a true crime show or following a real-life case, knowing how DNA evidence works—and its limitations—can provide deeper insights into the pursuit of justice.

After considering all the gathered information, including the use of mtDNA, the challenges posed by degraded and chemically treated samples, the limitations of DNA imputation, and the concerns about the chain of custody, I would finalize the estimate of the likelihood of Carl Webb being the Somerton Man at around 15-20%.

This final estimate reflects the compounded uncertainties and the significant limitations of the evidence available. While there is still some possibility, the cumulative impact of these factors substantially reduces the confidence in the identification.