This reference material serves as a guide for Army officers and noncommissioned officers who are responsible for the enforcement and maintenance of discipline and order in their respective units. Chapter 1 deals on the nature, concept, and principles of investigation. Chapter 2 deals on the investigation procedure as an important medium to ferret out truth while observing due process. Chapter 3 enumerates common offenses committed by military personnel; Chapter 4 enumerates and briefly discusses three (3) investigation agencies and the Courts of Inquiry. Presidential Decrees, AFP Circulars, Letter Directives, Special Laws enacted by Congress, and other related readings that deal with expeditious disposition of cases committed by Army personnel are also cited as annexes.