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

The Concept of Evidence

The main subject of any criminal defense investigator’s daily work is evidence. The need for evidence is why attorneys hire criminal defense investigators. Considering its underpinning aspects, evidence is a complex subject. This is true in both civil and criminal litigation. The subject of evidence can be viewed from two differing perspectives: first, through a consideration of why some information is consider evidence and other information is not and second, through a consideration of what evidence really is and how it is used to define a subject under question.

Critical Thinking

The criminal defense investigator’s primary task throughout any investigation is critical thinking. Beyond witness interviews and the overwhelming work of reviewing discovery material, the investigator is left with thought alone. Effective critical thinking skills differentiate a successful criminal defense investigator from one who will ultimately seek another niche in the for-profit investigations industry. A close examination of critical thinking reveals it to be a complex process of avoiding cognitive bias and stretching the imagination beyond first impressions.

Critical thinking emerges in three different forms: inductive, deductive, and abductive. All three forms overlap to some degree. Critical thinking in practice is a combination of all three forms in the development of “analytical beliefs.”

Inductive reasoning refers to generalization. This reasoning accounts for an array of possibilities but equally weights each possibility. In simple terms, this approach incorporates all possibilities and does not favor a specific one. Deductive reasoning differs from inductive reasoning regarding generalization. Instead, deductive reasoning focuses on a specific possibility, eliminating other possibilities based on the information available. In the end, a single, final possibility is favored. The pitfall of this form of reasoning is the risk of deception. The investigator’s judgements can be anticipated, and misleading information can cause the investigator to reach an incorrect judgement. Abductive reasoning, in essence, is a combination of inductive and deductive reasoning, moving from generalizations or specifics to an array of possibilities weighted unequally. In simple terms, abductive reasoning examines all possibilities creating “novel means of explanation,” thus reaching the most likely conclusion.

There is no doubt that critical thinking is a complex process rife with the risk of failure. As less-than-rational individuals, we construct a simplified model of the world around us to deal with a highly complex reality. As a result, we then “behave rationally within” our simplified view of reality. A criminal defense investigator is faced with this very process of simplifying reality. We may advocate for the defendant, or we may fail to benefit the defendant. In either case, simplifying the process of investigation for us as criminal defense investigators. From one of the two positions, we can simplify the overall process. This is the most generalized example of simplification but nevertheless illustrates it. The “tendency of people to perceive what they expect to perceive is more important than any tendency to perceive what they want to perceive.” Thus, our perception is a critical element in assessing information.

We make judgements based upon our perception of reality. How do we see reality? In general, individual perception of reality will vary depending on a person’s background, education, and cultural foundation. For example, most law enforcement officers may perceive themselves as the “good guys.” In turn, a law enforcement officer may see anyone who resists their authority and judgements as a “bad guy.” In this view, all members of the defense are “bad guys,” criminal defense investigators included! This perception of the “good guys” versus the “bad guys” is a prime example of simplification. The process of simplification is further strengthened through mental shortcuts.

We process information daily, and in doing so we tend to make mental shortcuts. These mental shortcuts are referred to as “heuristics.” One of the most important heuristics is the “availability heuristic.” Simply stated, the availability heuristic is when individuals predict the probability of something based upon the most immediately available example. For example, you assume a task is easily completed because everyone you know has completed the task with ease. You base this judgment on available information or events you have observed. The representative heuristic entails processing information that you are familiar with, as a consequence leading you to misjudge the information. For example, if you observe a dirty person walking down the street carrying a large bag, you would most likely assume the person is homeless, unless you are aware of information to the contrary. The label of “homeless” is the most available example for you to interpret your observations of the person. This is a simple example of how familiarity can be misleading and cause an error in judgement.

A criminal defense investigator must avoid all possible forms of bias. The concepts and methods presented in this book are specifically intended to uncover critical information that is often hidden in bias. A criminal defense investigator must be in constant pursuit of overcoming bias in order to enable objective results.

Understanding Information as Evidence

The perception and context of evidence used during an investigation is key. At times, the perception and context will be simple, and at other times they will be highly complex. In general, perception and context are used during an investigation to uncover the truth or understand what may be believed as the truth with a given degree of certainty. A given degree of certainty is a key aspect in any form of analysis during an investigation. In reality, the truth during any investigation is an abstract theoretical concept. In simple terms, truth does not exist.

During any investigation, the investigator can present evidence but can never present the truth with absolute, one-hundred percent certainty. The professional investigator is left viewing the investigation through a theoretical lens based on degrees of certainty. In the end, any professional investigator will finish an investigation with a low, high, or inconclusive degree of certainty, but the absolute truth will always remain elusive.

Evidence is a term used to define the proof of a theory or argument. In simple terms, evidence is based on perception. An item or event is evidence because we perceive it as evidence. Based on what is perceived as evidence, individuals make judgements using their “bias, distortions, uninformed logic, or downright prejudiced views.” Determining something to be evidence is based on the viewer’s perception of reality. Evidence is not truth; it is a fragment of the truth, a fragment that perceptions rest upon. Perceptions are directly tied to how the investigator perceives evidence and the context in which the evidence is examined. Beyond all technical terminology, evidence is simply information that is known and considered to define a specific phenomenon.

The Evidence Approach and Context Model

The terms “approach” and “context” deal directly with how the criminal defense investigator systematically responds to alleged evidence and the context from which the evidence is perceived. In simple terms, approach and context pertain to how evidence is interacted with in a given environment and how the evidence is perceived. Fortunately, we have a clear model to work from, which is depicted in Figure 4.1.

The model represents the perception and context used in a criminal defense investigator’s analysis. The model is a high-level framework used as a theoretical lens. In general, the model represents how evidence should be perceived and processed from the perspective of making analytical judgments during an investigation.

This model’s foundation is comprised of evidence from the perspective of guilt and innocence. Evidence credibility and evidence theory are built upon this initial evidence. In simple terms, this model can be understood using the concept of building blocks. The foundation must exist before any additional blocks can be built on top of it. During the entire investigative process, evidence is repeatedly collected, processed, and interpreted through the Evidence Perception and Context Model.

To fully understand the theoretical lens employed within this model, and to further refine the structured analytical techniques embedded in it, several key terms must be defined. These terms are useful for processing and understanding the spectrum of evidence encountered during an investigation.
Evidence of innocence is simply defined as evidence proving the innocence of the accused. Evidence of guilt proves the accused is guilty of an alleged crime. Both forms of evidence are refined through evidence credibility, which is defined as the degree of belief in a specific facet of evidence. An evidence theory, or an Alternative Evidence Theory from the criminal defense investigator's view, is defined as the available competing views of a specific evidence’s support for an array of possible criminal theories supporting innocence or guilt. Evidence of innocence, evidence of guilt, and the Alternative Evidence Theory are utilized to identify, collect, process, and interpret alleged evidence during the investigation of an alleged crime.

Understanding and identifying the difference between Evidence of innocence and Evidence of guilt is a complex and rigorous process. Unfortunately, historically this process has been based on initiative reasoning, which is prone to error. To fully evaluate the worth of specific evidence in proving innocence or guilt, more in-depth perception and context must be utilized, beyond simplistic intuitive reasoning. The credibility and theoretical interpretation of specific evidence has to be taken into account.
Evidence credibility is impacted by a wide array of factors. Credibility of evidence can range from low confidence to high confidence. The factors impacting this range vary depending on the type of evidence, which can include information gathered from deceptive witnesses and improperly collected or preserved physical evidence. From the perspective of the criminal defense investigator, evidence credibility is of special importance during a criminal defense investigation. The grim reality is that some evidence brought forth by the State has a low confidence level, for example, a witness providing incriminating testimony against a defendant based upon observations made during low-light conditions. How credible are the witness's observations? The criminal defense investigator has the responsibility of not only identifying this low confidence but also uncovering evidence that proves the specific evidence is of low quality. In terms of the above example, the criminal defense investigator would conduct a vision study to determine the quality of the witness's observation in the low-light environment. Evidence credibility is a key factor in any criminal defense investigation.

The Alternative Evidence Theory is based upon the perceptions of the observer and in many cases, upon close examination, will support a wide array of possibilities. In simple terms, the concept behind the Alternative Evidence Theory is that a facet of evidence can represent opposing interpretations or even any number of interpretations. For example, a fingerprint found on a murder victim's body can represent two opposing interpretations. The fingerprint is either the byproduct of the murderer touching the victim, or it represents the intimate touch of the victim's romantic lover. Thus, a specific facet of evidence can support more than one interpretation.
The Alternative Evidence Theory is the foundation of the criminal defense investigator's work. Generating an Alternative Evidence Theory is no simple task. A casual observer will most likely easily generate an alternative theory for specific evidence regarding the event in question. However, a layman’s attempt is typically substandard and collapses easily under scrutiny. A holistic approach is required to adequately generate an Alternative Evidence Theory. To enable a holistic approach, evidence is placed in three categories: evidence, silent evidence, and absent evidence.

The first category, “evidence,” incorporates all known information related to a specific phenomenon or, simply stated, an event. This information can vary wildly in form from witness testimony to physical evidence. Nevertheless, evidence is the information available for use in defining a specific event. For the criminal defense investigator, an event equals an alleged crime. The use of a specific facet of information used to define an event will vary depending on the bias or objective of the consumer of the information. For example, there will be differences in the ways the same information is used by the prosecutor and the defense attorney. Both parties will utilize the information to define the event in direct relation to their end goal of proving guilt or innocence. However, viewed holistically, the information defines the event and demonstrates what is known of the event.
The second category, “silent evidence,” pertains to information that is unknown. This is a complex issue experienced during most investigations. Simply stated, silent evidence represents information that has not been discovered and may never be discovered. It cannot be utilized to make any form of judgement and essentially represents a true unknown facet of an event. For example, during a rape investigation, the State fails to collect biological material from the alleged crime scene, specifically, the bed sheets. This alleged rape occurred days before the alleged victim made the allegation. The bed sheets represent silent evidence because no information is known regarding the biological material that may or may not have existed on the bed sheets. The most critical issue with silent evidence is the inability to confirm its existence. If the criminal defense investigator could confirm the existence or nonexistence of the information, it would no longer silent evidence; it’s proven existence would make it “evidence,” and its proven nonexistence would make it “absent evidence.”
The third category, “absent evidence,” is a theoretical form of evidence largely overlooked by novice investigators. Simply stated, absent evidence is information that in theory should exist but does not exist. Why is this form of evidence theoretical? For absent evidence to exist an incorrect theory must be proposed. For example, for an act of theft to have occurred, items of value must be unaccounted for. The missing items of value are directly tied to the theory of theft. If no items were unaccounted for, would a theory of theft withstand scrutiny? No, because the existence of the items of value is the “absent evidence” needed for the theory of theft. The concept of absent evidence can be challenging to apply during complex investigations. The key is to determine specifically what information should exist and then confirm its nonexistence. If it is confirmed, then the information is silent evidence.
Investigative Evidentiary Equation

From an investigative evidentiary standpoint, and event can be described using the Investigative Evidentiary Equation:

Event = Evidence + Silent Evidence - Absent Evidence - Credibility

The Investigative Evidentiary Equation defines an event using a holistic approach. All forms of evidence are considered and are interdependent. How does one from of evidence impact another? This is a critical question for understanding how information defines an event. “Evidence” is known information, and “silent evidence” is unknown information. “absent evidence” is an indicator of a theoretical error in judgement. Credibility is not a form of evidence but is a reflection of just how real the information is or, simply stated, whether the information actually exists in the context presented. Combined, these variables define the full spectrum of knowledge regarding a specific event. All known information collectively is the foundation of knowledge of a specific event. Silent evidence represents the gaps in this knowledge. From a practical standpoint, silent evidence is information that could prove our belief wrong, known as the unforeseen. In turn, silent evidence is always a lingering issue during any investigation and is directly tied to the need for an investigation. Absent evidence is negative information that reduces the degree of certainty of known information when placed in context of the event as a whole.
Evidence credibility is a negative aspect that addresses specific facets of information, for example, specific physical evidence or a single segment of witness testimony. Evidence credibility is not evidence but rather a reflection of how the information actually exists in the context presented. For example, is a specific witness providing false information? What degree of certainty exists in the witness testimony as presented? These are common questions asked when determining the credibility of a witness's testimony. In practice, all information is considered credible unless some information exists that calls that credibility into question. Thus, a negative is created in the overall information spectrum defining the subject event.

The holistic approach of the Investigative Evidentiary Equation is based on known information, or evidence. Silent evidence, unknown information, is added to the known information. The sum of these defines an event. Absent evidence acts as a negative factor in defining the event. The key to understanding this evidence equation is that evidence and silent evidence will always exist; absent evidence will only exist during analytical errors in judgment. Evidence credibility is only a factor when information exists that creates a question of credibility. Evidence and silent evidence are the core information. Absent evidence and evidence credibility only address the interpretation of evidence and silent evidence. This is why absent evidence and evidence credibility act as negative factors in the Investigative Evidentiary Equation.

Silent evidence is key to understanding the Alternative Evidence Theory. How can the sum of evidence, the known information, and silent evidence, the unknown information, define an event? Moreover, how does this concept have any utility in a criminal defense investigation? Simply stated, the purpose of an investigation is to uncover the unknown information. On the other hand, the concept has a much broader application within an investigation. The unknown information may always remain unknown. In theory, there will always be a facet of information that remains unknown, and because of this, persistent unknown information can never be established with an absolute degree of certainty. However, through diagnostic methods and harnessing the known information, a reasonable degree of certainty can be established. The critical aspect of silent evidence is the application of hypothesis generation and testing. Through the use of hypotheses, alternative interpretations of information can be generated.

The issue of evidence perception is uniquely important to the criminal defense investigator. Not only is the criminal defense investigator required to set aside any personal bias and consistently check their own logic, but they must also address the possibility that available evidence can support more than one interpretation of an event. All possible interpretations, as well as the underlining quality of evidence supporting each possible interpretation, must be evaluated.