This book is meant to be a reference book for ambulance investigators. Its primary focus is the importance of the investigative unit's database, especially databasing information from individual complaints, as well as self-generated investigations. It includes a concept called "the family of complaint types", which lists 494 related reports. Additionally, there are 543 other database reports that pertain to one or more of 46 investigative categories. From an investigative point-of-view the book covers what information should be databased, why so much information should be databased, the investigative benefits of entering so much information into the database, four sources for statistical information, the presentation of investigative stats, and lastly, the importance of a yearly Investigative Unit recap report. The first section covers a potpourri of topics which are not database related. These topics include information on complaints, what we can learn from complaints, investigations and cases, a formal investigative process, the importance of contacting the complainant as soon as possible after being assigned the case, a coverup is always worse than the original incident, negative EMS perception, the Media, the use of drones in EMS investigations, investigative vital signs, and the history of the investigative unit. The remainder of the sections pertain to databasing.