Chapter 2 THE CRIME SCENE

Chapter 2THE CRIME SCENE FORENSIC SCIENCE: An Introduction by Richard Saferstein

Arrival at the Crime Scene • Upon arrival at a crime scene the first responding police officer to a crime scene is responsible for: • Acquiring medical assistance for injured victims • Medical personnel avoid disturbing evidence and approach the victim by an indirect route. • Detaining any potential suspects or witnesses • Statements are taken from victims, witnesses, and suspects. (continued) FORENSIC SCIENCE: An Introduction by Richard Saferstein

Arrival at the Crime Scene • Securing the crime scene to the greatest extent possible • The boundary is sealed off, and guards are posted at the entry to the crime scene if needed. • All civilians and unauthorized personnel are excluded from the crime scene. • Calling for any additional personnel needs such as other officers and/or forensic investigators. • The personnel required depends upon the nature of the crime scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Securing the Crime Scene • The boundaries of the crime scene must be secured with crime scene tape, ropes, or cones. • The secured area should include the area where the crime took place and the surrounding area where physical evidence may be located. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Securing the Crime Scene • Once the boundaries are secured, guards may be posted to restrict access to the crime scene. • A detailed log is kept of personnel movements in and out of the crime scene. This log includes personnel names and time of entry or exit. • Investigators should never do anything that might alter the crime scene including smoking, eating, drinking, or littering. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Searching the Crime Scene • The search for physical evidence at a crime scene must be thorough and systematic. • The search pattern selected will normally depend on the size and locale of the scene and the number of collectors participating in the search. • For a factual, unbiased reconstruction of the crime, the investigator, relying upon his or her training and experience, must not overlook any pertinent evidence. • Physical evidence can be anything from massive objects to microscopic traces. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Recording Methods • Photography, sketches, and notes are the three methods for crime-scene recording. Ideally, all three should be employed • However, as is often the case, personnel and monetary limitations may prohibit the utilization of photography at every crime site. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Notes • Note taking begins when the investigator is contacted and requested to report to the crime scene. • The crime scene notes should begin with: • The identity of person who contacted the investigator • Time of contact and arrival at the crime scene • Preliminary case information • Personnel present on arrival and those being contacted FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Notes • Notes contain a personnel log, all observations made by the investigator, and the time observations were made. • Notes are taken in a uniform layout, concurrently as the observations are made. • Notes are written in a bound notebook in blue or black ink. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Digital Photography • A digital photograph is made when a light sensitive microchip captures light on each of millions of tiny picture elements, called pixels. • The light is recorded on each pixel as a specific electric charge that is read by the camera as image information, which is then stored as a file on a memory card. • The number of pixels is directly related to the resolution of the picture. Photographs with more pixels show increasingly good resolution, or more detail and sharpness in photographs. • The number of pixels that a camera features is usually measured in millions of pixels, or megapixels. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Digital Crime Scene Photography • Advantages of digital crime scene photography include: • The ability to observe images immediately after taking them ensures important photographs are clear and show the best possible detail. • The resolution available can exceed 12 megapixels, while the maximum resolution offered by a film SLR camera is equivalent to about 5 megapixels. • Computer programs can stitch digital crime scene images together to create a 3-D view of the crime scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Photography • Crime scene photographs should record the area in which the crime actually took place and all adjacent areas where important acts occurred. • The most important prerequisite for photographing a crime scene is for it to be in unaltered condition. • Each crime scene should be photographed as completely as possible in a logical succession. The sequence will show the overall scene first, then work down to individual pieces of evidence that jurors in the trial can easily relate back to the larger scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Photography • The four minimum photographs required at a crime scene are: an overview photograph, a medium range photograph, a close-up photograph, and a close-up photograph with a scale. • Overview photographs of the entire scene and surrounding area, including points of exit and entry, are taken first. • Taken from the outside borders of the scene and from various angles • If the crime scene includes a body, photographs must show the body’s position and location relative to the entire scene. • Include a “visual tag,” an object recorded in multiple overview photographs, to help visually piece the scene together FORENSIC SCIENCE: An Introduction by Richard Saferstein

PHOTOGRAPHY FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Photography • Medium-range photographs show the layout of smaller significant areas of the crime scene: • Taken with evidence markers in place to show the spatial relationships between and among pieces of evidence in greater detail than the overview photographs. • Include at least one photograph of the “center” of the scene. • In violent crimes, this usually includes the site where the victim was found and the surrounding area. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Photography • Close-up photographs are taken last and show greater detail of individual objects or evidence: • Taken at a 90º angle to the object, with and without evidence markers and scales. • Scales should be placed as close to the evidence as possible without affecting it in any way. • After the 90º photographs have been taken, photographs from other angles may be taken. • The most important close-up photographs are those depicting injuries and weapons lying near a body. • After the body is removed from the scene, the surface beneath the body should be photographed. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Videotaping Crime Scenes • As with still crime scene photography, the crime scene video must include overview, medium-range, and close-up images. • A narrated crime scene video combines photography and notes. • However, it is important that only one person narrates and no side conversations are captured on the video. • Some video cameras can produce still photographs, but the quality is often poor. • Therefore, still photographs from a digital camera are still required. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Surveying the Crime Scene • The Walkthrough—initial survey of the crime scene • Perpetrator’s point of entry and exit are located. • Indirect path is taken to the center of the crime scene. • Obvious items of evidence are located and documented. • The conditions of the scene are observed and recorded. • Special attention is paid to item or conditions that suggest timing of the incident or do not appear to belong. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Searching the Crime Scene • Line/Strip Search Pattern • One or two investigators start at the boundary of the crime scene and search in straight lines across to the other side of the crime scene. • Grid Search Pattern • Two or more investigators form a grid by searching in line patterns that overlap and are perpendicular to each other. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Searching the Crime Scene • Spiral Search Pattern • One investigators searches in a spiral path from the center of the crime scene to the boundary (outward) or from the boundary of the crime scene to the center (inward). • Wheel/Ray Search Pattern • Several investigators search in straight lines from the center to the boundary (outward) or from the boundary to the center (inward). • Quadrant/Zone Search Pattern • The crime scene is divided into smaller sections (zones). One or more investigators are assigned to search each zone. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Figure 2–11Several typical examples of crime-scene search patterns. The pattern selected normally depends on the size and locale of the scene and the number of collectors participating in the search. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Searching the Crime Scene • Vehicle Searches: • Investigators search interior and exterior of vehicle. • The vehicle may be searched at the crime scene or at the police department or crime laboratory garage. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Sketching the Crime Scene • Crime scene sketches: • Clearly show the layout of a crime scene • Illustrate the relationship in space of all significant items and features • Clarify objects and features already described in notes or shown in photographs • Show measurements over long distances and topography of outdoor scenes • Depict possible paths of entry, exit, and movement through the scene FORENSIC SCIENCE: An Introduction by Richard Saferstein

The Rough Crime Scene Sketch • A rough sketch is created at the crime scene and contains an accurate depiction of the dimensions of the scene and shows the location of all pertinent objects and features. • All rough sketches include: • Title block with information on the case, crime scene, and person creating the sketch • Legend with identity and dimensions of objects in the sketch • Compass showing the North direction • Body containing the sketch itself • Points of reference for objects can be shown by the distance measurements from two fixed points. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Rough-sketch diagram of a crime scene Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, NC:www.sirchie.com FORENSIC SCIENCE: An Introduction by Richard Saferstein

The Finished Crime Scene Sketch • The finished sketch is created from the information in rough sketch, but it is drawn to scale with care and concern for appearance. • The current standard method utilizes Computer-Aided Drafting (CAD) programs to create the finished sketch. • CAD programs also allow for the creation of three-dimensional finished sketches. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, NC:www.sirchie.com FORENSIC SCIENCE: An Introduction by Richard Saferstein

Procedures for Collection • Often, many items of evidence are clearly visible but others may be detected only through examination at the crime laboratory. • For this reason, it is important to collect possible carriers of trace evidence, such as clothing, vacuum sweepings, and fingernail scrapings, in addition to more discernible items. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Procedures for Collection • Investigators handle and process physical evidence in a way that prevents changes to the evidence through contamination, breakage, evaporation, accidental scratching or bending, or through improper or careless packaging. • The use of latex gloves, disposable forceps, and sanitized equipment reduces the chance for contamination. • Whenever possible, one should keep evidence in its original condition as found at the crime scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Packaging • Each different item or similar items collected at different locations must be placed in separate containers. Packaging evidence separately prevents damage through contact and prevents cross-contamination. • The well-prepared evidence collector will arrive at a crime scene with a large assortment of packaging materials and tools ready to encounter any type of situation. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Packaging • Disposable forceps and similar tools may have to be used to pick up small items. • Unbreakable plastic pill bottles with pressure lids are excellent containers for hairs, glass, fibers, and various other kinds of small or trace evidence. • Alternatively, manila envelopes, screw-cap glass vials, or cardboard pillboxes are adequate containers for most trace evidence encountered at crime sites. • Ordinary mailing envelopes should not be used as evidence containers because powders and fine particles will leak out of their corners. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Packaging • Sealable plastic evidence bags. • Small amounts of trace evidence can also be conveniently packaged in a carefully folded paper, using what is known as a “druggist fold.” • Evidence from arson scenes should be packaged in airtight metal or glass containers to prevent the loss of accelerant vapors. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Packaging • If biological or bloodstained materials are stored in airtight containers, the accumulation of moisture may encourage the growth of mold, which can destroy the evidential value. • In these instances, the material should be allowed to air-dry before being packaged in wrapping paper, manila envelopes, or paper bags. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Packaging • Contamination is a key concern during the collection of DNA-containing specimens, such as blood, saliva, sweat or skin cells. Contamination can occur either by introducing foreign DNA through coughing or sneezing onto evidence or if items of evidence are incorrectly placed in contact with each other during packaging. • To prevent contamination, the evidence collector must wear a face mask and lab coat, use disposable latex gloves and work with disposable forceps when collecting evidence that may contain DNA. • Disposable coveralls, shoe covers, and eye protection offer added precautions to avoid contaminating DNA evidence. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Chain of Custody • Chain of Custody: A list of all persons who came into possession of an item of evidence. • Continuity of possession, or the chain of custody, must be established whenever evidence is presented in court as an exhibit. • Adherence to standard procedures in recording the location of evidence, marking it for identification, and properly completing evidence submission forms for laboratory analysis is critical to chain of custody. • This means that every person who handled or examined the evidence and where it is at all times must be accounted for. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Obtaining Reference Samples • Standard/Reference Sample: Physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence. • The examination of evidence, whether it is soil, blood, glass, hair, fibers, and so on, often requires comparison with a known standard/reference sample. • Although most investigators have little difficulty recognizing and collecting relevant crime-scene evidence, few seem aware of the necessity and importance of providing the crime lab with a thorough sampling of standard/reference materials. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Departing the Crime Scene • The experienced lead investigator decides when all pertinent physical evidence has been recorded and collected at the crime scene. • A final survey is undertaken to review the scene visually and collect all evidence and equipment. • Following the final survey, the crime scene is released to the proper authorities. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Submitting Evidence • Evidence is usually submitted to the laboratory either by personal delivery or by mail shipment. • Care must be taken in packaging evidence that will be sent by mail in order to prevent breakage or other accidental destruction during transit to the laboratory. • Most laboratories require that an evidence submission form accompany all evidence submitted. Case information provided on this form enables the laboratory analyst to make an intelligent and complete examination of the evidence. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Safety • Crime scenes frequently present the investigator with biological specimens of unknown origin. • The investigator has no way of gauging what health hazards they may contain. • One must use caution and protection at all times. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Safety • It is recommended that personnel always wear latex gloves and possibly chemical resistant clothing, Tyvek-type shoe covers, a particle mask/respirator, goggles, or face shields when potentially infectious material is present. Gloves should be changed often. • Personnel should maintain a red biohazard plastic bag for the disposal of contaminated gloves, clothing, masks, pencils, wrapping paper, and so on. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Crime Scene Safety • When processing and collecting evidence at a crime scene, personnel should be alert to sharp objects, knives, hypodermic syringes, razor blades, and similar items. • Eating, drinking, smoking, eating, and chewing gum are prohibited at the immediate crime scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein

Chapter 2 THE CRIME SCENE