Chapter 3Investigators, the

Investigative Process, and the Crime Scene

© 2009 McGraw-Hill Higher Education. All rights reserved.

Learning Objectives

• Understand the role of the investigator and skills and qualities they must possess

• Discuss major events in the investigation of a crime

• Explain the major steps in a preliminary investigation

• Describe activities conducted in a follow-up investigation

• Define a crime scene• Outline purposes and functions of an

investigator

© 2009 McGraw-Hill Higher Education. All rights reserved.

Chapter Objectives

• Explain the “rules” for the crime scene investigator

• Identify potential threats to investigators’ health and safety

• Be familiar with major considerations that dominate the crime scene search

• Be able to discuss investigation of staged crime scenes

• Explain crime scene reconstruction

© 2009 McGraw-Hill Higher Education. All rights reserved.

WHAT IS A CRIME?

• A crime is the commission or omission of any act, which is prohibited or required by the penal code of an organized political state, to which some punishment or sanction is attached.

• Classifications– Felony

• Punishable by death or imprisonment for more than one year in a state prison.

– Misdemeanor• Punishable by fine and/or imprisonment for up to one year in a

local or county jail.

– Infraction or Violation• Minor offenses punishable by a fine only.

© 2009 McGraw-Hill Higher Education. All rights reserved.

THE INVESTIGATOR

Someone who gathers, documents and evaluates evidence.

– Strong professional training and experience– Strong degree of self-discipline– Uses legally approved & ethical methods– Does not act out of malice or bias– Includes all evidence of innocence as well as guilt– Uses systematic methods of inquiry– Uses both inductive and deductive reasoning– Compassionate, not calloused and cynical– Has wide ranging contacts across many occupations– Remains objective at all times– Leaves nothing to chance during investigation

© 2009 McGraw-Hill Higher Education. All rights reserved.

THE INVESTIGATIVE PROCESS

• Objectives– Establish if a crime was

committed– Collect, document and

preserve evidence– Identify and apprehend

the suspect(s)– Recover stolen property– Assist in the prosecution of

the person(s) charged with the crime(s)

Major events in the investigation of a

crime

© 2009 McGraw-Hill Higher Education. All rights reserved.

THE PRELIMINARY INVESTIGATION

• The actions taken at the scene of a crime immediately following its detection and report to the police– Receipt of information

and initial response– Emergency care– Crime scene control– BOLO alerts– Crime scene

determination– Evidence – The report

© 2009 McGraw-Hill Higher Education. All rights reserved.

FOLLOW-UP INVESTIGATION

• Subsequent investigation– Contacting witnesses who left the scene– Checking out suspect(s) alibi– Gathering additional evidence from other locations– Talk with informants– Attempt to locate additional witnesses– Evaluate evidence collected and laboratory results of tests– Obtain search and/or arrest warrants– Recover stolen property– Confer with prosecutor

© 2009 McGraw-Hill Higher Education. All rights reserved.

CRIME SCENE

• Location where the offense was committed– May include surrounding areas where evidence may

be located– Always start big . . . It’s much easier to make it

smaller than to expand it at a later time– There may be more than one crime scene– Macroscopic versus Microscopic scenes

© 2009 McGraw-Hill Higher Education. All rights reserved.

Crime Scene continued

Crime-scene investigators examine blood-stained clothes before placing them in an evidence bag.

© 2009 McGraw-Hill Higher Education. All rights reserved.

Rules for the Crime Scene Investigation

• Maintain Control• Conceptualize Events• Proceed with Caution• Apply Inclusiveness• Maintain Documentation

Chief Charles Moose addresses the news during

the Washington D.C. sniper investigation.

(©AP/Wide World Photos)

© 2009 McGraw-Hill Higher Education. All rights reserved.

ORGANIZATION OF THE CRIME SCENE

• Overall coordination– Handled by assigned case agent– Power to call in additional resources & coordinate all

investigative activities

• Technical services– Crime laboratory personnel & supervisors

• Investigative services– Interviewing witnesses and victims– Neighborhood canvass– Suspect field interrogations

© 2009 McGraw-Hill Higher Education. All rights reserved.

CATEGORIES OF EVIDENCE

• Corpus Delicti evidence– Evidence that helps to prove the elements of the

crime(s)

• Associative evidence– Evidence that connects the suspect to the scene

and/or victim or connects the scene/victim to the suspect

• It is bidirectional

• Trace evidence– Small or microscopic evidence, or evidence in

limited amounts

© 2009 McGraw-Hill Higher Education. All rights reserved.

EVIDENCE RECOVERY LOG

• A chronological record of who found what evidence, where, witnessed by whom, and notations about other ways the evidence may have been documented, e.g., photography

© 2009 McGraw-Hill Higher Education. All rights reserved.

EVIDENCE RECOVERY LOG

The evidence recovery log is an important document which records all pieces of physical evidence found at a crime

scene. This is critical if the case is to be successfully prosecuted later.

© 2009 McGraw-Hill Higher Education. All rights reserved.

CRIME SCENE CONTROL

• The actions which the first arriving officer at the crime scene takes to make sure that the integrity of the scene is maintained.

• Control also includes preventing people at the scene from becoming combatants and separating witnesses.

© 2009 McGraw-Hill Higher Education. All rights reserved.

CONCEPTUALIZATION

• Keep known facts AND inferences in mind when processing scene– Facilitates reconstruction of the offense– Identification of the modus operandi– Identification of certain types of evidence– Assists in establishing investigative direction

© 2009 McGraw-Hill Higher Education. All rights reserved.

CAUTION

• Don’t destroy evidence• Make crime scene bigger than expected and

shrink as necessary• Don’t overlook fruitful areas for exploration• Do more than a cursory examination

© 2009 McGraw-Hill Higher Education. All rights reserved.

INCLUSIVENESS

• Obtain every piece of evidence• If not sure, take it as evidence until it is ruled

out• Do not dismiss items of possible evidence

– Be careful of rationalization and fatigue

© 2009 McGraw-Hill Higher Education. All rights reserved.

DOCUMENTATION

• Constant Activity– Starts with rough shorthand field notes– Sketches– Diagrams to scale

• WAYS TO DOCUMENT A CRIME SCENE VISUALLY INCLUDE:– Video taping– Photographing– Sketching

(Courtesy Lewiston, Maine, Police Department)

© 2009 McGraw-Hill Higher Education. All rights reserved.

THREATS TO INVESTIGATORS HEALTH AND SAFETY AT CRIME SCENES

• Insect bites• HIV/AIDS• Hepatitis B and C • Tuberculosis

© 2009 McGraw-Hill Higher Education. All rights reserved.

MAJOR CONSIDERATIONS OF THE CRIME SCENE SEARCH

• Boundary Determination • Choice of Search Patterns• Instruction of Personnel• Coordination• Documentation

© 2009 McGraw-Hill Higher Education. All rights reserved.

CRIME SCENE SEARCH PATTERNS

The crime scene coordinator may choose from a variety of crime scene search patterns based upon the type and size of the crime scene.

© 2009 McGraw-Hill Higher Education. All rights reserved.

Crime Scene

Police diver recovers a handgun as part of an underwater investigation.