Military Defense Investigation Knowledge Base
Military Defense Investigation Authority Publication
Authority Publication No. DI-121
Polygraphs in Military Investigations
Independent Military Defense Investigations
Supporting Attorneys, Service Members, and Families
Publication Date: August 24, 2026
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Executive Summary
Polygraphs in military investigations can influence interviews, evidence interpretation, and later investigative decisions even when the reported result is not admissible.
Polygraphs can affect a military investigation in ways that extend beyond the reported result. The examination process may include a pretest interview, examiner statements, additional questioning, and post-test communications that become part of the investigative record.
DI-121 focuses on what the defense should examine when a polygraph has influenced the course of a case. The investigator should preserve the original materials, identify who created and controlled them, and reconstruct what investigators knew before the examination and what they did afterward.
The publication emphasizes a source-based approach. Leads, verified facts, inferences, and conclusions should remain separate. Later investigative decisions should be tested against independent evidence rather than assumed to be reliable merely because they followed a reported polygraph result.
The objective is not to reject government evidence automatically. It is to determine what exists, how it was obtained, whether it is complete and reliable, and what additional evidence could confirm or contradict the material point.
A polygraph may influence a military investigation even when the reported result is not admissible. DI-121 explains how the defense can reconstruct the examination, source record, chronology, and later investigative decisions to determine what the evidence actually supports.
Who Should Read This Publication?
Military Defense Counsel
Use the reconstructed examination and decision sequence to evaluate what later investigative steps were independently supported and what may require additional discovery, expert review, or legal analysis.
Defense Investigators
Preserve and map the request, consent, rights warnings, recording, examiner materials, communications, reports, quality review, and later investigative actions.
Service Members
Understand that the significance of a polygraph investigation may extend beyond a reported result to statements, follow-up questioning, and later investigative decisions.
Experts
Review complete underlying materials and clearly defined questions when specialized analysis of examination procedures, statements, recordings, or related evidence is required.
Families
Understand why defense counsel and investigators need the original records and complete chronology rather than relying on a simplified 'pass/fail' description.
Companion Video
This companion video expands on the investigative concepts presented in this Authority Publication through additional explanation, practical examples, and professional investigative insight.
About Michael West
The investigative guidance presented throughout these Authority Publications is based upon decades of professional experience conducting military, federal, criminal, civil, and private investigations. The principles discussed in these publications are drawn from real investigative work involving complex cases, witness development, evidence analysis, and factual case preparation.
Michael West has served as a Special Agent with the United States Air Force Office of Special Investigations (AFOSI) and the Department of Defense Inspector General, conducted federal background investigations, and spent decades working as a licensed private investigator supporting attorneys, businesses, service members, and private clients. Throughout his career, his work has focused on identifying facts, locating witnesses, analyzing evidence, and strengthening the factual foundation of legal cases through independent investigation.
The Military Defense Investigation Knowledge Base was created to share that investigative experience in a practical, understandable format. Its purpose is to help attorneys, service members, and families better understand the investigative process, ask more informed questions, and recognize opportunities where independent investigation may strengthen the defense.
Important Information
This Authority Publication is provided for educational and informational purposes and is intended to help readers better understand military defense investigations and the investigative process. It is based upon professional investigative experience and is designed to provide practical investigative insight rather than legal advice.
Every military case is unique. The investigative strategies, factual issues, and legal considerations applicable to one case may not apply to another. Readers should consult with a qualified attorney regarding legal rights, legal strategy, and decisions involving their individual circumstances.
Nothing contained in this publication should be interpreted as creating an attorney-client relationship or an investigator-client relationship. References to investigative techniques, procedures, or case examples are provided solely to illustrate investigative principles and should not be considered legal guidance.
Effective military defense is strengthened by informed legal representation supported by thorough factual investigation. The purpose of these Authority Publications is to help readers better understand that investigative process so they can communicate more effectively with qualified legal counsel and make informed decisions throughout the military justice process.