The Crime Scene

Physical Evidence and The Crime Scene Physical evidence is any and all objects that can establish that a crime has or has not been committed or can link a crime and its victim or its perpetrator. Can’t collect everything-you have to be selective and collect the most important pieces of evidence to be evaluated in the crime lab. Evidence at a crime scene must be preserved and recorded in its original condition as much as possible.

Secure and Isolate the Crime Scene It is the job of the first officer on the scene to preserve and protect the area as much as possible. Use ropes or tape to create a perimeter and place guards in strategic areas to keep everyone else out! The lead investigator then starts evaluating the scene and determines the perpetrator’s path of entry and exit. Items of interest must be documented and photographed.

3 methods for crime scene recording: Record The Scene Records of the crime scene in its original state will be used in the subsequent investigation, as well as at trial if necessary. 3 methods for crime scene recording: Photography Sketches Notes Ideally, all three should be used but photography is not always available so sketching and notes should be done at the very minimum.

Photographing the Scene The prerequisite for photographing a crime scene is for it to be unaltered. If objects are moved, positions changed, etc. before the scene is photographed, it must be documented in the notes. Most departments use a digital camera with at least 4 megapixels but 12 or more is the most desirable. Photographs can show: Line of sight of victims, suspects, or witnesses Biological evidence in its original state

Photographic Procedures At a minimum, 4 types of photographs are required: Overview photograph-shows the entire area and all adjacent areas where important acts occurred before or after the crime, points of entry and exit, if a crime scene includes a body-the body’s position and location relative to the rest of the scene must be shown and once the body is removed, pictures of the area under the body should be taken. Medium-Range photographs-as physical evidence is discovered, photographs should be taken of the objects in relation to the rest of the scene. Close-Up photographs-used to record the details of the object. Close-Up photographs with a scale-a ruler is placed in the photograph to show the relative size of the object.

Sketches Done after the photographs have been taken. 2 Types: Rough Sketch: the initial sketch of the scene that shows accurate dimensions of the scene and the location of all objects that are important to the case. Objects in a rough sketch are usually depicted by a number or a letter and a key is included with the sketch. The position of objects is also denoted by accurate measurements made with a tape measure from two fixed points, like a wall. The sketch should also show a compass heading designating North. Finished Sketch: usually done with a computer-aided drafting (CAD) program and must include all items from the rough sketch. Many symbols that allow a more detailed description of the scene, like blood spatter. Can be scaled to produce larger images for court and also close ups of interested areas of the crime scene.

Rough Sketch Finished Sketch

Notes Note taking must be constant and must include: A detailed written description of the scene Location of items of physical evidence recovered Time an item was discovered Who it was discovered by How and by whom it was packaged and marked Who took the item from the scene Remember that this record must be sufficiently detailed because it might be the only source of information for refreshing one’s memory weeks, months or even years down the road. Audio recordings are a faster way to take notes at the scene, however, they have to be transcribed into a written document soon after their recording.

Safety at The Crime Scene Before a scene can be processed, the first responding officers should make sure that the scene is not only secure, but also safe for investigators to enter. Check for anything that might be an immediate threat to an officer’s life-such as moving vehicles, electrical damage, fire, etc. Investigators must use caution and protect themselves at all times from contracting AIDS or hepatitis. Bodily fluids must always be treated as though they were infectious. Investigators commonly use dust particle masks at a crime scene because they are considered disposable and should be discarded after a single use. Investigators should always wear latex or nitrile gloves, chemical-resistant clothing, Tyvek-type shoe coverings, a particle mask, goggles, and possible face shields when potentially infectious material is present. Gloves should be changed often when processing a crime scene. Investigators should be alert to sharp objects, knives, hypodermic needles, razor blades, and similar items at a scene. Eating, drinking, smoking, and chewing gum are prohibited at the scene.