This modest book presents the Department of Justice’s Department Circular No. 015, series of 2024 or the “2024 Department of Justice-National Prosecution Service (2024 DOJ-NPS) Rules on Preliminary Investigations and Inquest Proceedings.” The 2024 DOJ-NPS Rules on Preliminary Investigations and Inquest Proceedings now govern the conduct of preliminary investigations and inquest proceedings in all prosecution offices in the National Prosecution Service of the Department of Justice. Further, these Rules govern crimes or offenses where the penalty prescribed by law is at least six years and 1 day without regard to fine. (See Sec. 3). The book aims to provide law and criminology/criminal justice students, as well as the general public, with a greater familiarity with the new rules on preliminary Investigations and inquests (governing crimes where the imposable penalty is at least six years and 1 day).