Crime Scene Investigation (CSI)

As Paul Kirk, the noted forensic science pioneer, described it, forensic science is

interested in the “unlikely and the unusual” (Kirk, 1963, p. 368). This is certainly

true of crime scenes: Each one is unique. The crime committed, the location, the

items used, the people involved, all vary from scene to scene. Although nearly

every police and forensic agency has written protocols about processing

a crime scene, these may be trumped by the circumstances of the crime

scene. As Barry Fisher, retired Director of the Los Angeles County Sheriff’s

Department Crime Laboratory notes, “There are few absolute rules in crime scene

investigations . . . . There are always cases where guidelines cannot be followed . . . .

Situations demand that investigators be flexible and creative when necessary”

(2004, p. 49). That is, crime scene investigators (or CSIs, for short), must know and

follow their agency’s protocols but must be ready to improvise, within accepted

limits, to protect and/or preserve evidence.

First on the Scene

The success of any crime scene investigation depends in large part on

the actions taken in the first few minutes after the First Officer (or FO, for

short) or CSI arrives. This sounds odd, to be sure. “How can a few minutes

matter to a crime scene that’s just been sitting there for hours or days?”

one may ask. But crime scenes are a complex mix of static and dynamic

information, a scene fixed in time like a photograph but slowly degrading,

much like poorly archived historical photographs. The majority of the

physical evidence will be generated by the processing of the crime scene,

and the relationships between the people, places, and things (the context)

will tell the story of what happened. Remember, facts alone are not

sufficient; by themselves, they explain nothing. Facts must be interpreted

in light of the circumstances or context surrounding the crime. Once an

item is moved, it can never be placed back exactly as it was: The context

is disturbed, and the subsequent interpretation may be biased and

inaccurate.

The primary task of the FO at a crime scene is to secure the scene and prevent

destruction or alteration of the critical and sometimes fragile context of a crime scene.

The assumption is that the perpetrator has left physical evidence at the crime

scene. Therefore, the FO’s duties are simple in concept but complex in execution:

1. Detain any potential suspects.

2. Render medical assistance to those who need it.

3. Do not destroy, alter, or add any evidence at the scene.

4. Prevent others, even superiors, from doing the same.

But not all crime scenes are equal. A homicide in a small house’s bedroom

is certainly easier to seal and guard than a body found in the middle of a

wooded park or a busy highway. The FO should not simply rush into a scene but approach it carefully, thoughtfully. Sometimes the best thing to do is just

prevent further entry until additional agency staff arrive.

Once the immediate scene is secured, the lead investigator further defines

and evaluates the scene. The scene may be large or small, extensive or

discrete, made up of several locations or centered in one area. With the crime

scene defined and its borders identified, the initial surveyor begins to develop

an overview and devise a plan of action.

Plan of Action
Preparation

• Obtain a search warrant, if necessary.
• Discuss the search with involved personnel before arrival at the scene, if possible.
• Establish a command headquarters for communication and decision making in major or complicated crime scene searches.
• Ensure that personnel are aware of the types of evidence usually encountered and the proper handling of the evidence.
• Make preliminary personnel assignments before arrival at the scene, if possible.
• Ensure that assignments are in keeping with the attitude, aptitude, training, and experience of personnel. Personnel may be assigned two or more responsibilities.
• Person In Charge
  • scene security
  • administrative log
  • preliminary survey
  • narrative description
  • problem resolution
  • final decision making
• Photographer
  • photography and log
• Sketch Preparer
  • sketch and log
• Evidence Recorder
  • evidence custodian and log
• Establish communication between medical examiners, laboratory personnel, and prosecutive attorneys so that questions during the crime scene search can be resolved.
• Coordinate agreements with all agencies in multijurisdictional crime scene searches.
• Accumulate evidence collection and packaging materials and equipment.
• Prepare the paperwork to document the search.
• Provide protective clothing, communication, lighting, shelter, transportation, equipment, food, water, medical assistance, and security for personnel.
• In prolonged searches, use shifts of two or more teams.
• Transfer paperwork and responsibility in a preplanned manner from one team to the next.

Secure the Scene, Secure the Item

• Take control of the scene immediately.
• Determine the extent to which the scene has been protected. Obtain information from personnel who have knowledge of the original condition.
• Designate one person in charge for final decision making and problem resolution.
• Continue to take extensive notes.
• Keep out unauthorized personnel.
• Record who enters and leaves.

Preliminary Survey

• The survey is an organizational stage to plan for the search.
• Cautiously walk through the scene.
• Maintain administrative and emotional control.
• Select a narrative technique such as written, audio, or video.
• Take preliminary photographs.
• Delineate the extent of the search area. Usually expand the initial perimeter.
• Organize methods and procedures.
• Recognize special problem areas.
• Identify and protect transient physical evidence.
• Determine personnel and equipment needs. Make specific assignments.
• Develop a general theory of the crime.
• Take extensive notes to document the scene, physical and environmental conditions, and personnel movements.

Photography

• Photograph the crime scene as soon as possible.
• Prepare a photographic log that records all photographs and a description and location of evidence.
• Establish a progression of overall, medium, and close-up views of the crime scene.
• Photograph from eye level to represent the normal view.
• Photograph the most fragile areas of the crime scene first.
• Photograph all stages of the crime scene investigation, including discoveries.
• Photograph the condition of evidence before recovery.
• Photograph the evidence in detail and include a scale, the photographer's initials, and the date.
• When a scale is used, first take a photograph without the scale.
• Photograph the interior crime scene in an overall and overlapping series using a wide-angle lens.
• Photograph the exterior crime scene, establishing the location of the scene by a series of overall photographs including a landmark. Photographs should have 360 of coverage. Consider using aerial photography.
• Photograph entrances and exits.
• Photograph important evidence twice.
• A medium-distance photograph that shows the evidence and its position to other evidence.
• A close-up photograph that includes a scale and fills the frame.
• Acquire prior photographs, blueprints, or maps of the scene.

Sketch


Crime scene sketches may look crude at times, but they contain one very
important element for reconstruction: numbers. Distances, angles, time,
temperature—all these elements make the crime scene sketch, an example
of which is shown in Figure 2.2, central to all subsequent work. Sketches
complement photographs and vice versa. Items of evidence can be located on
the sketch as it is made to help establish locations later. Although sketches are
quantitative, they are normally not drawn to scale. However, sketches should
have measurements and details for a drawn-to-scale diagram. A sketch should
include the following:
• The case identifier
• Date, time, and location
• Weather and lighting conditions
• Identity and assignments of personnel
• Dimensions of rooms, furniture, doors, and windows
• Distances between objects, persons, bodies, entrances, and exits
• An arrow pointing toward magnetic north


Chain of Custody


Arguably, the single most important piece of paper generated at a crime
scene is the chain of custody. This form, an example of which is shown in
Figure 2.3, documents the movement of evidence from the time it is obtained
to the time it is presented in court. The most compelling evidence in the
world can be rendered useless if inaccuracies or gaps exist in a chain of
custody. Where was the evidence? Who had control of it? When? Who last
had this item? Could it have been tampered with during this gap in time?
Having to document each exchange of an item from person, to evidence
locker, to person, to agency may seem to be a nuisance, but it is the
foundation that permits forensic science results to enter into a courtroom.


Crime Scene Search and Evidence Collection

• Use a search pattern such as a grid, strip or lane, or spiral.
• Search from the general to the specific for evidence.
• Be alert for all evidence.
• Search entrances and exits.
• Photograph all items before collection and notate the photographic log.
• Mark evidence locations on the sketch.
• Complete the evidence log with notations for each item of evidence. If feasible, have one person serve as evidence custodian.
• Two persons should observe evidence in place, during recovery, and being marked for identification. If feasible, mark directly on the evidence.
• Wear gloves to avoid leaving fingerprints.
• Do not excessively handle the evidence after recovery.
• Seal all evidence packages at the crime scene.
• Obtain known standards such as fiber samples from a known carpet.
• Make a complete evaluation of the crime scene.
• Constantly check paperwork, packaging, and other information for errors.

  Spiral method  Grid Method Strip or lane method

Final Survey

• The final survey is a review of all aspects of the search.
• Discuss the search with all personnel.
• Ensure all documentation is correct and complete.
• Photograph the scene showing the final condition.
• Ensure all evidence is secured.
• Ensure all equipment is retrieved.
• Ensure hiding places or difficult access areas have not been overlooked.

Release

• Release the crime scene after the final survey.
• Crime scene release documentation should include the time and date of release, to whom released, and by whom released.
• Ensure that the evidence is collected according to legal requirements, documented, and marked for identification.
• Consider the need for specialists such as a blood-pattern analyst or a medical examiner to observe the scene before it is released.
• Once the scene has been released, reentry may require a warrant.
• The scene should be released only when all personnel are satisfied that the scene was searched correctly and completely.
• Only the person in charge should release the scene.