First Officer Attending
Despite the variation among crime scenes, there is a standard procedure in place to ensure a scene is handled in an appropriate manner. When a crime is initially reported, the first officer attending will have a number of duties to complete whilst waiting for other personnel to arrive. The FOA must carry out an initial assessment of the situation, dealing with any emergencies as necessary. Any individuals already present at the scene, including witnesses and suspects, must be detained, should it be necessary to conduct any interviews or even make arrests. The FOA himself will informally interview any relevant persons in order to determine whether a crime has actually been committed and if any emergency aid is required, such as the summoning of paramedics. If first aid is given, the officer should take note of anything that is altered during life-saving efforts, such as the movement of victims or objects. When scientific support personnel arrive at the scene, the FOA will share any relevant information he has gained with them.
Crime Scene Preservation
The barriers of a crime scene are established, ensuring that all vital pieces of evidence plus entrances and exits are included, and a physical barrier placed around the scene. This barrier may be crime scene tape, police officers standing guard, barricades or vehicles. This barrier essentially controls who enters the scene, aiming to exclude all non-essential personnel. A log is produced noting all individuals who do cross the barrier and the times at which they enter and exit. As the scene and its evidence may be partially or wholly exposed to the elements, protection from weather damage may be required. This can be accomplished by simply using clean cardboard boxes to cover the relevant areas, or in some instances a tent may be erected. All individuals entering the scene should wear the correct protecting clothing, which may consist of a set of overalls, latex gloves, paper shoes, and even a face mask. Upon leaving the scene, all protecting clothing worn throughout the investigation should be collected for analysis to avoid the risk of losing valuable trace evidence.
Crime Scene Processing
During the systematic search for evidence, a leading investigator will often assign individuals to particular areas of the crime scene whilst overlooking the search for and collection of evidence. The way in which the scene is processed will often be determined by the nature of the crime. Indoor crime scenes will be quite simply searched on a room-by-room basis, whereas outdoor crime scenes may require a more detailed search pattern. There are a number of search patterns that may be followed:
Zone or quadrant search: The scene is divided into smaller, manageable portions which are searched individually.
Lane, line or strip search: Officers form a line and move on side-by-side, covering the entire scene together.
Spiral search: The investigator begins at the epicentre of the room and moves outwards in a spiral pattern. Or alternatively the investigator starts at the edge of the scene and spirals into the centre.
Wheel search: Investigators begin at the epicentre of the scene and move outwards, each in a straight line in a different direction.
Recording the Crime Scene
Before anything is moved or even touched, the entire scene must be fully documented to ensure a permanent record exists of the scene in the state in which it was found. This documentation may include written notes, photographs, video recording, and sketches. Extensive notes will be kept for each item of physical evidence recovered from the scene, including the location in which it was found, who collected it and at what time, and a description of the item itself. General notes regarding the scene itself will also be taken, including environmental details, information on the state in which the scene was found, and any other details that may be relevant. Sketches are frequently used to show the locations, dimensions and orientations of objects of significant found at the scene, and relevant measurements. Photography is perhaps the most important form of crime scene documentation, producing a permanent visual record of the crime scene and discovered evidence. Extensive photographs should be taken of all areas of the crime scene and every item of evidence collected. See the forensic photography page for a more detailed description.
Recovery of Physical Evidence
When documentation of the scene is complete, the scene of crime officers can then proceed to collect physical evidence from the scene. The nature of the evidence itself will determine the method of collection and how it is contained. It may be necessary to focus on the collection of certain evidence first, namely items that may be particularly fragile or valuable to the investigation. If a body is present at the scene, it will often be impossible to touch or move the victim until the necessary specialist has arrived at the scene, such as the pathologist. Before the body is transported to the mortuary, plastic bags are secured over the head, hands and feet to prevent the loss of trace evidence.
Packaging of Physical Evidence
As with recovery methods, the packaging of physical evidence is dependant on the nature of the evidence. All items collected should be packaged, stored and transported in such a way that prevents any change or damage from taking place between the time it is recovered and the time it is received by the laboratory. Small, dry item may be folded in paper and then sealed in polythene bags, whereas wet items should be sealed in polythene bags and frozen, especially if they contain potential biological samples. Every item collected should be placed in a separate container to prevent damage through contact and cross-contamination. Finally, all pieces of physical evidence should be labelled with any identifying information regarding the item, plus the location in which it was found, the crime it relates to, and the date and signature of all persons involved in its recovery.