The Duties of the Criminal Defense Investigator

Most people have a vague idea of what a criminal defense investigator does.

Some assume the job is about “finding loopholes” or “helping people get away with things.”

In reality, the role is far more structured—and far more serious—than that.

The investigator’s role is to help ensure that the defense has complete, accurate information so decisions are made fairly, responsibly, and based on the full picture—not assumptions, shortcuts, or incomplete records.

When this work is done correctly, it strengthens the integrity of the entire justice process. Below is what that work actually looks like in practice.

1. Ensuring the Defense Has All Discovery

The foundation of any case review is discovery: police reports, supplemental narratives, body-worn camera footage, dispatch audio, photographs, forensic reports, lab results, and other materials generated during an investigation.

One of the first responsibilities of a defense investigator is confirming that all discoverable material has been received. This may sound basic, but it is critical. Missing items matter. A single overlooked recording, photograph, or supplemental report can significantly change how an event is understood.

This step protects against decisions being made in the dark. You cannot evaluate a case you haven’t fully seen. This work is about completeness—not conclusions.

2. Reviewing Reports, Audio, Video, and Photographs

Reviewing discovery is not a cursory read-through.

Written reports are compared against audio and video recordings. Timelines are examined. Photographs are reviewed alongside written descriptions. Body-worn camera footage is assessed not only for what it shows, but sometimes for what it does not show.

Differences between sources do not automatically mean anyone acted improperly. More often, they reflect the reality of high-stress situations, limited perspectives, and human memory. Identifying those differences early allows counsel to understand where clarification is needed before decisions are made.

This review helps ensure that the written record accurately reflects what actually occurred.

3. Issue Spotting

Issue spotting is one of the core analytical responsibilities of a defense investigator. It involves identifying questions that still need to be answered before a case moves forward.

This may include:

• Timeline inconsistencies

• Evidentiary gaps

• Procedural questions

• Missing context

• Conflicts between different accounts

  
  

Issue spotting is not about creating problems where none exist. It is about identifying unanswered questions early, while they can still be responsibly addressed. Well-spotted issues protect the integrity of the process by ensuring that decisions are based on verified facts rather than assumptions.

When done properly, this step benefits everyone involved.

4. Confirming Victim and Witness Statements

Victims and witnesses are human beings, not transcripts. Stress affects perception. Time alters recall. Even small misunderstandings can change how a written statement reads months or years later.

Confirming statements is not about challenging someone’s experience or minimizing harm. It is about ensuring that what is written accurately reflects what was said—and what was meant. In some cases, clarification strengthens the original account. In others, it provides context that was not captured during an initial interview.

Accuracy matters because written statements often carry significant weight long after the moment has passed.

5. Contacting New or Overlooked Witnesses

Scenes are dynamic. Not everyone present is identified during an initial response. Some witnesses leave before officers arrive. Others are not interviewed. Some people come forward only later, once emotions settle or concerns about involvement ease.

A defense investigator may locate and interview additional witnesses to better understand the environment, sequence of events, or surrounding circumstances.

A new witness can support an existing narrative, contradict it, or add complexity. All three outcomes matter. The goal is not a particular answer—it is a more complete and accurate understanding of what occurred.

6. Working With Experts

Some cases involve technical or specialized evidence that requires expert interpretation. This may include forensic evidence, medical issues, accident reconstruction, or digital data.

Defense investigators work with qualified experts to understand what the evidence actually shows, what conclusions can reasonably be drawn, and where limitations exist. Experts are not there to advocate for outcomes. Their role is to explain complex information so it can be evaluated responsibly.

This step helps ensure that technical evidence is understood—not misunderstood.

7. Testifying When Required

Defense investigators may be called to testify about their work. That testimony is given under oath and is subject to cross-examination.

Because of this, documentation, accuracy, and professional discipline matter at every stage of an investigation. An investigator’s credibility is built case by case and can be tested in a matter of minutes on the stand. This reality reinforces why careful, methodical work is essential from the beginning.

8. Assisting Counsel at the Defense Table

Criminal defense is not a solo effort.

During hearings or trial, investigators often assist counsel by managing exhibits, tracking witnesses, organizing evidence, and helping ensure that information is presented clearly and accurately. They serve as an additional set of trained eyes and ears, supporting the attorney so proceedings remain organized and responsive to what unfolds in real time.

This behind-the-scenes support helps the process function smoothly and professionally.

The Bigger Picture

Criminal defense investigators are advocates for process, accuracy, and completeness.

When the system works as intended, every decision—whether it leads to dismissal, resolution, or trial—is made with full information and professional care. That benefits not only defendants, but victims, courts, and the public as a whole.

A fair system depends on diligence at every stage. The work of a criminal defense investigator exists to help ensure that fairness is real, not assumed—and that decisions affecting people’s lives are made carefully, responsibly, and with respect for the truth.