Military Defense Investigation Knowledge Base
Military Defense Investigation Authority Publication
Authority Publication No. DI-099
Understanding DNA Mixtures, Transfer, and Statistical Claims from a Defense Perspective
Independent Military Defense Investigations
Supporting Attorneys, Service Members, and Families
Publication Date: August 31, 2026
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Executive Summary
DNA evidence can be scientifically powerful, but a statistic is not a complete account of what happened. Detection, possible source, statistical weight, transfer mechanism, deposition time, and alleged activity are separate questions that should not be blended together.
Authority Publication DI-099 explains how defense teams examine sample location, collection method, mixture complexity, possible contributors, analytical thresholds, assumptions, drop-in and drop-out, interpretation methods, validation, and the proposition addressed by the reported statistic.
The publication also discusses direct, secondary, tertiary, and environmental transfer. A person's DNA may reach another person or object through indirect, multiple-step contact, so the presence of a profile does not by itself establish direct contact, timing, transfer route, or connection to the alleged conduct.
A defense-oriented guide to separating DNA detection, source attribution, mixture interpretation, transfer pathways, activity questions, and statistical weight.
What readers will learn
- Separate source-level findings from transfer and activity-level propositions.
- Identify mixture complexity, assumptions, thresholds, and possible contributors.
- Evaluate direct, secondary, tertiary, and environmental transfer pathways.
- Understand what a likelihood ratio compares—and what it does not prove.
- Document collection context, legitimate access, contamination controls, and limitations.
Who Should Read This Publication?
Military Defense Counsel
Use this publication to identify the proposition actually in dispute, prevent source-level statistics from being overstated, and frame focused requests for expert assistance.
Defense Investigators
Learn how to document sample location, handling history, legitimate access, possible transfer routes, environmental context, and alternative explanations for deposition.
Service Members
Understand that the presence of DNA may identify a possible contributor without proving when the material arrived, how it moved, or what activity occurred.
Experts
Use a clearly defined question and complete contextual record to explain mixture interpretation, statistical propositions, transfer possibilities, validation, and scientific limitations.
Families
Learn why ordinary contact, shared objects, prior access, and multiple-step transfer may matter and why case-related items should be preserved rather than cleaned, handled, or tested informally.
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.