Criminal Defense Investigation: Theory, Practice, and Methods

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Recommended citation:

Pennington, Jeremy. Criminal Defense Investigation: Theory, Practice, and Methods. Ironton: Pennington & Associates Ltd., 2016


This book specifically addresses the professional practice of criminal defense investigators. Although there are many aspects that could be addressed, this book’s focus is on the analytical skills needed to undertake the endeavor of criminal defense investigations. There are many aspects of a criminal defense investigator’s profession that the reader will still have questions about after finishing this book. These areas, however, are domain specific and therefore not the focus here. In many cases, this book describes these areas in general terms; however, it is not my intention to delve into specific domains of knowledge that deal with particular forensic issues and investigative tradecraft. An abundance of literature already exists on those topics, and any attempt to tackle them in this book would only be redundant and in vain.

Amongst all available literature on criminal investigations one thing is very apparent: there is a high degree of focus on collection methods. In simple terms, this means the practice of collecting information referred to as evidence. This may seem appropriate considering the purpose of a criminal investigations. However, this selective focus on information gathering has devastating consequences on the assessment and interpretation of the evidence uncovered through a criminal investigation. This book diverts from this main focus in the literature by drawing attention to the assessment and interpretation of evidence, not just its collection.

Including collection methodologies in this book may be appropriate, but it would also be redundant. Professional investigators, both public and private, have access to volumes of literature written on collection methods, the range of which covers witness interviews to the collection of physical evidence. Moreover, including collection methods within this book would offer only a limited view of specific areas; volumes would be needed to properly cover this material.

The analytical theory and skills required in criminal investigations, specifically in criminal defense investigations, represents an overwhelming gap in current literature. Many academics and working professionals would argue that methods of evidence analysis are covered; however, this is simply not true. For example, the available literature on analysis in forensic science has an extremely limited focus on results: the identification of blood, the matching of latent fingerprints, toxicology, and the list goes on. The resulting analysis is simply another form of evidence that must be incorporated into the overall reconstruction of past events. The criminal investigator, in the end, is left with the task of interpreting the final results of any given forensic process.

In order to fill this void in the literature, this book specifically addresses analytical methodologies and processes and is aimed at professional practicing criminal defense investigators. However, these same methodologies and processes are applicable to law enforcement investigations. In practice, the methods are the same no matter which side of the courtroom is presenting its results.

While drafting this book, considerable focus was given to the simplicity of its presentation. Although this book could have been written in a more technical format with considerable complexity, the end goal was that the material would be clear and easy to use. That said, many of the topics presented are complex. Unlike books that spend page after page trying to drive home a point through differing points of view, this book presents information from the perspective of what you need to know and not to prove a particular point. Many topics require the reader to obtain real life experience and apply the methods and practices presented in order to fully understand them. A reader of this book should consume the information and then, simply, put it into practice. Much like the concepts underpinning complex math, the information presented in this book requires effort on the part of the reader for full comprehension.