Understanding and Mitigating Errors in Digital Forensics

Introduction

In forensic science, errors are inevitable, and acknowledging their existence is crucial for ensuring the reliability and accuracy of forensic work. This is especially true in digital forensics (DF), where the support provided to law enforcement is fundamental to many investigations. Errors in forensic practice can have significant consequences, impacting the outcomes of investigations and the lives of those involved. This article explores the concept of error within the field of digital forensics, identifying potential sources of error and mapping them to the stages of the investigative process to assist practitioners in addressing and mitigating these errors effectively.

What is an Error?

The Oxford English Dictionary defines an error as “a mistake,”. In forensic contexts, it refers to deviations from accuracy or correctness. Errors can be systematic, random, or due to negligence, and recognizing them requires understanding the correct behavior for any given process. It is also important to distinguish errors from mistakes; errors are competence-based deviations due to a lack of knowledge, while mistakes are performance-related despite having the necessary knowledge.

Recognizing the Importance of Errors

Errors in forensic science can have catastrophic consequences, leading to public mistrust and unsafe legal decisions. However, errors can also serve as valuable learning experiences, facilitating improving current and future practices. Forensic practitioners must strive to understand and correct errors, using them to enhance the robustness of investigative techniques and overall practice.

Attribution of Error

Attributing errors to a source is crucial for improving practices and preventing repeat occurrences. This involves identifying the origin of the error and understanding the causal factors that contributed to it. This process is not about placing blame but ensuring long-term improvements in forensic practices.

Forms of Error

Errors in digital forensics can be broadly categorized into systematic, random, and negligent errors. Systematic errors are reproducible inaccuracies due to equipment or process issues, random errors vary from one measurement to another, and negligent errors result from incorrect operations by the practitioner. These errors can occur across multiple stages of an investigation.

Mapping Sources of Error to the Investigative Process

The digital forensic investigative process can be broken down into several key stages: Incident Response, Review of Client Requirements, Identification, Handling, Preservation & Collection, Exhibit Handling, Data Acquisition, Data Processing/Examination, Analysis, Interpretation and Evaluation, Presentation of Findings for Peer Review, and Presentation/Communication of Results. Throughout these stages, errors can originate from six main sources: client errors, wider investigative/forensic team errors, practitioner errors, tool/instrument errors, method errors, and trace errors.

Client Error

Clients, including victims, defendants, instructing counsels, and officers in charge (OIC), play a crucial role in the forensic process. Errors can occur when clients provide incorrect or incomplete information, fail to understand the forensic capabilities, or miscommunicate case requirements. These errors can impact the planning, seizure, and examination of digital evidence.

Wider Investigative/Forensic Team Error

Errors can also arise from the wider investigative team, including front-line police officers, law enforcement staff, and lab technicians. These errors may occur during the identification, handling, and seizure of digital devices, client requirements review, or exhibits in-lab processing. Miscommunication, incorrect method utilization, and administrative errors are common in these scenarios.

Practitioner Error

Practitioners can make errors in tool use, method choice, method deployment, method development, misinterpretation of case requirements, and result communication. These errors can stem from biases, incompetence, negligence, stress, lack of knowledge, and workload. Practitioner errors can significantly impact the quality and accuracy of forensic investigations.

Tool Error

Digital forensic tools are essential for examining and interpreting digital evidence. However, tools can have inherent errors due to source code, algorithm implementation, or configuration flaws. Practitioners must understand a tool’s scope of performance and use it correctly to avoid errors. Regular evaluation and validation of tools are necessary to ensure their reliability.

Method Error

Methods used in digital forensics must be valid, fit for purpose, and capable of producing repeatable and reproducible results. Errors can occur when the wrong method is chosen, incorrectly deployed, or a method is inherently flawed. Practitioners must ensure that methods are properly designed, validated, and deployed to prevent errors.

Trace Error

Digital traces, the focus of forensic examinations, can sometimes be erroneous. Trace errors occur when digital traces incorrectly represent the events they are intended to describe. These errors can lead to missed data, misrepresentation, and misinterpretation of evidence. Practitioners must carefully evaluate digital traces to ensure their reliability.

Conclusions

Errors are inevitable in digital forensic practice, and understanding their sources and impacts is crucial for quality assurance and improvement. By mapping errors to the stages of the investigative process, practitioners can better identify, manage, and mitigate these errors. Continuous evaluation and adaptation are necessary to address new sources of error and ensure the reliability and accuracy of digital forensic investigations.

License and Notes

This article is based on the original study “Sources of Error in Digital Forensics” by Graeme Horsman, published in Forensic Science International: Digital Investigation. The content is licensed under a Creative Commons Attribution 4.0 International License. Contents may be edited for style and length.

Study Reference: Horsman, G. (2024). Sources of error in digital forensics. Forensic Science International: Digital Investigation, 48, 301693. https://doi.org/10.1016/j.fsidi.2024.301693