How Do Crime Scene Investigators Examine a Crime Scene?

The Crime Team Arrives

Most crimes cannot be solved by a single individual. Teams of experts are required to properly investigate a crime scene. A senior investigating officer will oversee the scene-of-crime team that is mobilized to a site. This team is supervised by a crime scene manager, who is in turn monitored by a crime scene coordinator. Thus, investigations commonly occur within an atmosphere of stringent accountability.

The act of securing a crime scene involves both the removal of anyone who may disturb key evidence located at the scene and the removal of any harmful elements that may threaten the safety of crime scene investigators assigned to examine the scene. For example, a crime scene remains unsecured if a ticking bomb is discovered by investigators. Should the bomb explode, law enforcement officials may be killed or injured and valuable evidence may be destroyed (see Reference 1). Thus, securing a crime scene means doing everything possible to prevent evidence from getting tainted. To this purpose, crime scene investigators often establish an entry point for the crime scene where all visiting parties must identify themselves in a crime scene entry-control log.

Three important sources of testimony at a crime scene are suspects, witnesses and crime victims. Crime scene investigators try to quickly secure testimony from each of these sources as soon as a crime has been committed. Ideally, each source is interviewed separately so each person's testimony will be authentic and not influenced by other sources. Often, these initial statements will later be referred to if a case is tried in court, and are usually compared against any subsequent testimony. Criminals are apt to trip themselves up in their own lies as they embellish a story during repeated interrogation. Even law enforcement officials who arrive first at the scene of a crime should be interviewed in order to assist in establishing a chronology of events regarding the crime.

For decades, TV detectives have instructed their assistants to "dust for prints." After all of these years, fingerprint evidence is still prized as a valuable form of evidence in a crime scene investigation. However, recent advances in technology have allowed investigators to lifts prints off a wide range of surfaces. Other trace evidence, such as footprints and tire tracks, must be carefully preserved to prevent damage during handling (see Reference 2).

Physical evidence must be handled with care by crime scene investigators. The integrity of this evidence may be compromised if defense lawyers can prove it was not correctly labeled, tested or properly stored. Thus, investigators must establish that vital evidence, which may later be exhibited at trial, is in fact evidence that originates from a crime scene. They may do so by recording testimony from each person who takes the evidence "into custody" as it undergoes analysis. Each person must attest that the evidence is not altered at any stage prior to being employed in a court case (see Reference 3).