criminalistics - peoria public schools

Criminalistics An Introduction to Forensic Science

CHAPTER

Criminalistics: An Introduction to Forensic Science, 11e Richard Saferstein

Copyright © 2015 by Pearson Education, Inc. All Rights Reserved

ELEVENTH EDITION

The Crime Scene

2



Processing the Crime Scene

What are you there for???

PHYSICAL EVIDENCE!!

Definition: Any object that can establish that a crime has or has not been committed or can link a crime and its victim or its perpetrator.

Important to recognize what is

important and collect it properly.



Arrival at the Crime Scene

• Upon arrival at a crime scene the first responding police officer to a crime scene is responsible for:

1. Acquiring medical assistance for injured victims

• Medical personnel avoid disturbing evidence and approach the victim by an indirect route.

2. Detaining any potential suspects or witnesses

• Statements are taken from victims, witnesses, and suspects.




3. Securing the crime scene to the greatest extent possible

• The boundary is sealed off and secured with crime scene tape, ropes or cones.

• Officers are posted at the entry to the crime scene.

• The secured area should include the area where the crime took place and the surrounding area where physical evidence may be located.

• All civilians and unauthorized personnel are excluded from the crime scene.




4. 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.



Securing 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.



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.



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.



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



Crime Scene Notes

• Notes contain a personnel log, all observations made by the investigator, and the time observations were made. Include what was collected, by whom, where, and disposition after collection.

• 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 with no erasures. Incorrect entries must be crossed out and initialed.



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 which is read by the camera as image information which is stored as a file on a memory card.



Digital Photography

• 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.



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.



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.

• 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



FIGURE 2–4a This sequence of crime-scene photographs shows the proper progression of photographing the scene. The sequence begins with an overview photograph of the entry to the victim’s bedroom showing evidence markers in place. Richard Saferstein, Ph.D.



FIGURE 2–4b This sequence of crime-scene photographs shows the proper progression of photographing the scene. The medium-range photograph shows the evidence marker next to the door denoting a cartridge case. Richard Saferstein, Ph.D.



FIGURE 2–4c This sequence of crime-scene photographs shows the proper progression of photographing the scene. The close-up photograph shows the cartridge in detail with a scale in the photograph. Richard Saferstein, Ph.D.




• 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.




• Close-up photographs are taken last and show greater detail of individual objects or evidence.

Taken at a 90°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 90°photographs have been taken, photographs from other angles may be taken.




• Close-up photographs (cont.)

WHEN A BODY IS PRESENT - 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.



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.



Surveying the Crime Scene

• The Walkthrough—initial survey of the crime scene

1. Perpetrator’s point of entry and exit are located.

2. Indirect path is taken to the center of the crime scene.

3. Obvious items of evidence are located and documented.

4. 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.




• 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.




• 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.



FIGURE 2–11 (a) Strip or line search pattern. (b) Grid search pattern. (c) Spiral search pattern. (d) Wheel or ray search pattern. (e) Quadrant or zone search pattern.




• 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.



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



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



The Rough Crime Scene Sketch

• Points of reference for objects can be shown by the distance measurements from two fixed and immovable points.



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.



FIGURE 2–9 Finished-sketch diagram of a crime scene. Sirchie Fingerprint Laboratories



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.

• NEVER remove trace evidence at the scene! Transport entire object to the laboratory for processing.



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.



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.



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.



Packaging

• Ordinary mailing envelopes should not be used as evidence containers because powders and fine particles will leak out of their corners.

• 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. Sealable plastic evidence bags. (KAPAK)



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. (Store in a freezer)



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.



Packaging

• Disposable coveralls, shoe covers, and eye protection offer added precautions to avoid contaminating DNA evidence.



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.



Chain of Custody

• 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.



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.



Obtaining Reference Samples

• 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.



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 visually review the scene and collect all evidence and equipment.

• Following the final survey, the crime scene is released to the proper authorities.



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.



Submitting Evidence

• 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.



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.

• It is recommended that personnel always wear PPE (personal protective equipment) ie. latex gloves, 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.



Crime Scene Safety

• Personnel should maintain a red biohazard plastic bag for the disposal of contaminated gloves, clothing, masks, pencils, wrapping paper, and so on.

• When processing and collecting evidence at a crime scene, personnel should be alert to sharp objects, knives, hypodermic syringes, razor blades, and similar items.



Search and Seizure Protocols

• The removal of any evidence from a person or from the scene of a crime must be done in conformity with Fourth Amendment privileges:

“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizure, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”



Search and Seizure Protocols

• The United States Supreme Court has determined that search and seizure without a court-approved warrant is justified in four cases:

1. The existence of emergency circumstances

2. The need to prevent the immediate loss or destruction of evidence

3. A search of a person and property within the immediate control of the person provided it is made incident to a lawful arrest

4. A search made by consent of the parties involved



Search and Seizure Landmark Cases

• In the case of Mincey v. Arizona, the Court dealt with the legality of a four-day search at a homicide scene and determined that the evidence was illegally seized because a warrant was never issued and the circumstances of the case did not justify a warrantless search.



Search and Seizure Landmark Cases

• In Michigan v. Tyler, fire destroyed a business establishment leased by Loren Tyler and a business partner. The court decided that evidence obtained from the initial search was legally seized, but evidence obtained from searches 4, 7, and 24 days after the incident were illegally seized.

criminalistics - peoria public schools

Documents