A crime scene is the location where a criminal event occurs. It includes not only the immediate setting of the crime but all objects, areas and spaces associated with that crime that will serve as exhibits in a court case.
Crime scene processing requires careful examination, documentation and preservation. This process is a combination of physical measurements, photographs, sketches and extensive notes and observations. It must be carefully managed in order to avoid contamination and damage to evidence that could render it inadmissible in court.
The crime scene examiner begins by talking with the officer(s) who were the first on the scene and learning what has changed at the scene since their arrival. This can include turning lights on or off, opening doors and windows and other possible actions that could affect the integrity of the crime scene. The first investigator to re-enter the scene will take a photograph showing their proposed path of contamination and then, dressed in sterile crime scene attire, enter the scene in a manner that will minimize cross-contamination.
Once in the crime scene, the examiner should start with the primary area of interest (the room in which the body was found or the ransacked bedroom). Examiners should then expand their search to all accessible areas based on what they know about the circumstances.
The examiner should look for signs of the presence of a suspect at the scene. This can be indicated by footprints, discarded items and the presence of items that don’t belong in the scene such as a wallet on a bookshelf or a knife behind a stove. In addition to this, examiners should check for routes of entry and exit to the scene by the suspect – look under sinks, in cabinets, on top of furniture and behind books and bedclothes.