Chapter 2: The Crime Scene

Arrival at the Crime Scene

1. Acquiring medical assistance for injured victims
2. Arrest the suspect
3. secure the crime scene
4. Calling for any additional personnel, officers and/or forensic investigators

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.

\-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 that includes personal names and time of entry and exit. \n

Securing the crime scene

Investigators should never do anything to alter the crime scene

Searching the Crime Scene

The search for physical evidence at a crime scene must be thorough and systematic

Searching the crime scene

Physical evidence can be anything from massive objects to microscopic traces

Recording Methods

photography, sketches, notes

crime scene notes

Note taking begins when the investigator is contacted and requested to report to the crime scene.

Crime scene notes begin with

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

Personnel log, observations made by investigator, and time when observations were made. Notes are made in a uniform layout as the observations are made, notes are written in a bound notebook in blue or black ink

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. 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

The ability to observe images immediately after taking them, resolution can exceed 12 megapixels, maximum resolution by a SLR camera is 5 megapixels

Digital Crime Scene Photography

Computer programs can stitch digital crime scene images together to create 3-D view of the crime scene

Crime Scene Photography

Should record the area in which the crime took place, most important prerequisite for photographing is making sure the scene is unaltered

Crime Scene Photography

Each crime scene should be photographed as completely as possible in a logical succession

Four minimum photographs

overview, medium range, close up, close up with scale

Overview Photographs

Exit and entry, body and location of body, taken from outside border, includes visual tags

Medium range photographs

show the layout of similar 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 centre of the scene, where victim was found

Close up photographs

taken last and show greater detail of individual objects or evidence. Taken at 90 angel to the object with and without evidence markers and scales, depicts injuries and weapons, surface beneath the body

Videotaping Crime Scenes

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 film or digital camera are still required.

Surveying 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.

Searching the crime scene

Line/strip search, grid search, spiral search, wheel/ray search, quadrant/zone search

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.

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.

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, depict possible paths of entry and exit

A rough crime scene sketch

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, title block with information on the case, crime scene, and person creating the sketch, legend with identity and dimensions, 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

Finished Crime Scene Sketch

created from the information in rough sketch, but it is drawn to scale with care and concern for appearance, current standard method utilizes computer-aided- drafting (CAD) 3D programs to create the finished sketch

Procedures for collection

Many items of evidence are visible but others may be detected only through examination at the crime lab, it is important to collect possible carriers of trace evidence like clothing, vacuum sweepings, fingernail scrapings, investigators handle evidence in a way that prevents contamination. Latex gloves, disposable forceps, and sanitized equipment is used, keep evidence in its original condition

packaging

All items must be placed in separate containers, separating evidence reduces risk of contamination.

Unbreakable plastic pill bottles

Used to store hairs, glass, fibers, and other small trace evidence

cardboard pillboxes

screw cap glass vials

manila envelopes

Adequate for most trace evidence

druggist fold

Small amounts of trace evidence is packaged in carefully folded paper consisting of folding one end of the paper over one-third, then folding the other end over that and repeating the process from the other two sides

Airtight metal or glass containers

Evidence from arson scenes should be placed in those to prevent loss of accelerant vapors

Packaging (continued)

biological or bloodstained materials are should be allowed to air dry before being packaged in wrapping paper, manila envelopes, or paper bags

prevent contamination

Evidence collector must wear a face mask and lab coat, disposable coveralls, shoe covers, eye protection, use disposable latex gloves, and work with disposable forceps when collecting evidence that may contain DNA.

chain of custody

A list of all people who came into possession of an item of evidence

chain of custody

record location, marking for ID, properly completing evidence submission forms

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, examination of evidence requires comparison to standard/reference sample

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 when packaging evidence to be shipped, evidence submission form must also be required

Crime Scene Safety

Must use caution and protection at all times, wear latex gloves, chemical resistant clothing, shoe covers, a particle mask/respirator, goggles or face shields, gloves should be changed often

Disposing of equipment

Red biohazard bag to dispose of gloves, clothing, masks, pencils, wrapping paper

Crime Scene Safety

Be aware of sharp objects, eating smoking, drinking and chewing gum are prohibited at a crime scene

4th Amendment

Freedom from unreasonable searches and seizures

Search and seizure without a warrant

The existence of emergency circumstances, need to prevent loss or destruction of evidence, a search of a person and property within the immediate control of the person provided it is made incident to a lawful arrest, a search with consent from all parties

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.

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.