Mr. Michael Munn, M.A.
Mary Lara
02 March 2012
Criminal Investigation Principles
Crime today has become complex as human nature. The sophistification of how crimes are committed today and the challenging of certain laws have added substantial burden to those who have chosen careers within the Criminal Justice System to investigate and prosecute such criminals. Many concerns in conducting the various types of investigations has always been the legality of the “how’s”, “who’s” and “when’s”. The collecting of physical and DNA evidence, Interviewing of witnesses and the various types of surveillances used all fall into a closely watched category within the investigation process. Not only is it imperative that all types of investigations are done correctly but the ultimate goal of a successful conviction clearly depends on it. One of the critical and most important areas of any investigation is the collection of evidence. Whether it be physical evidence such as fingerprints, tire marks, footprints, fibers or DNA evidence this area is vital, it can be the only key to link someone to a crime. However, to play it role, the evidence must be collected and analyzed properly. Prior to any collection of evidence photographing and filming must be done. An important general principle in evidence collection and to have such evidence admissible in court is to have a secure chain of custody. That is each person who handled the evidence from its collection to its appearance in court must sign for it. Therefore, the court knows who had custody of it at each stage of its journey. Cross contamination is another crucial factor in evidence collection. According to the nature of the evidence, certain packaging methods and handling methods must be done. For instance, tape lifts of hair and fibers may be adhered to a piece of film and then sealed into a clean polythene bag. Fibers