1. Chapter 1
Criminal Investigation: An Overview
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2. Introduction
• An observant police officer can initiate an important
criminal investigation
• Criminal investigation combines art and science
• Requires extraordinary preparation and training
• High-tech society
• Citizens expect results more quickly
• Investigators need to step up their technology and
teamwork skills
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3. A Brief History of Criminal Investigation
HISTORICAL SIGNIFICANCE
• Bow Street Runners
• Vidocq Society
• Scotland Yard
• Pinkerton National
Detective Agency
• Major advances in criminal investigation
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4. Criminal Investigation Definitions
KEY DEFINITIONS
• Investigate
 Derived from Latin, vestigare, meaning to track or trace
• Criminal investigation

Discovering, collecting, preparing, identifying and
presenting evidence
• Deductive reasoning

Logical process; conclusion follows from specific facts
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5. Other Terms Defined
SPECIFIC TERMS
• Criminalist
• Forensic science
• Crime
• Felony
• Misdemeanor
Continued
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6. Other Terms Defined (Continued)
SPECIFIC TERMS
• Criminal statute
• Ordinance
• Elements of the crime
• Criminal intent
• Modus operandi, or MO
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7. Goals of Criminal Investigations
SUCCESSFUL INVESTIGATIONS
• Determine whether a crime has been committed
• Legally obtain information and evidence to identify the
responsible person
• Arrest the suspect
• Recover stolen property
• Present the best possible case to the prosecutor
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8. Basic Functions of Investigators
INVESTIGATOR FUNCTIONS
• Provide emergency assistance
• Secure the crime scene
• Photograph, videotape and sketch
• Take notes and write reports
• Search for, obtain and process physical evidence
Continued
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9. Basic Functions of Investigators (Continued)
INVESTIGATOR FUNCTIONS
• Obtain information from witnesses and suspects
• Identify suspects
• Conduct raids, surveillances, stakeouts and undercover
assignments
• Testify in court
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10. Characteristics of an Effective Investigator
SPECIFIC CHARACTER TRAITS
• Intellectual
• Psychological
• Physical
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11. An Overview of the Investigative Process
INVESTIGATIVE PROCESS
• Usually initiated by personal observation or
information from a citizen
• Starts with a direction to proceed to a scene
• Department policy defines who responds
• Department policy defines duties of individuals
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12. The Preliminary Investigation:
Basic Considerations
THE INITIAL RESPONSE
• Suspect may still be at or near the scene
• Injured persons may need emergency care
• Witnesses may still be at the scene
• Dying person may have confession/information
• Weather may change/destroy evidence
• Crime scene may be altered
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13. The Preliminary Investigation:
Basic Considerations
POINT OF ARRIVAL
• Scene may be either
utter confusion or
deserted
SETTING PRIORITIES
• Handle emergencies first
• Secure the scene
• Investigate
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14. The Preliminary Investigation:
Basic Considerations
HANDLING EMERGENCY SITUATIONS
• Sometimes emergencies dictate procedure
• Emergency situations causes the adrenaline to flow
SUSPECT AT OR NEAR THE SCENE
• Policy determines interrogations
• Miranda warning
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15. The Preliminary Investigation:
Basic Considerations
PERSON IS SERIOUSLY INJURED
• Emergency first aid
• Call for medical assistance
• Accompany suspects to hospital
DEAD BODY AT SCENE
• Leave the body as found
• Preserve the scene
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16. The Preliminary Investigation:
Basic Considerations
PROTECTING THE CRIME SCENE
• Major responsibility of the
first officers to arrive
• Locard’s principle of exchange
• Scene is critical
• Maintain security
• Protect from destruction or
alteration from the elements
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17. The Preliminary Investigation:
Basic Considerations
CONDUCTING THE PRELIMINARY
INVESTIGATION
• Questioning
• Neighborhood canvass
• Measuring, photographing,
videotaping and sketching
• Searching for evidence
• Processing physical evidence
• Recording all statements
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18. Crime Scene Investigators
SCIENTIFIC SPECIALIST
• Specialist in organized scientific collection and
processing of evidence
• Processes and packages all physical evidence
• Attends and documents autopsies
• Writes reports and testifies in court
• Crime scene technology degree
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19. The Follow-Up Investigation
FACTORS FOR FOLLOW-UP
• Many cases require a follow-up investigation
• Factors exist that are beyond the officers’ control
• Weather can destroy evidence
• Witnesses can be uncooperative
• Follow-up phase builds on what was learned
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20. Computer-Aided Investigation
CRIME ANALYSIS, MAPPING AND GEOGRAPHICAL
INFORMATION SYSTEMS
• Crime mapping and hot spots
DATA MINING
• Sifting through information
• Helps narrow the field of possible suspects
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21. Problem-Oriented Policing
DEPARTMENT-WIDE STRATEGY
• Aimed at solving persistent community problems
• Identify, analyze and respond
• Used in criminal investigations in many ways
• Combining problem-oriented strategies with traditional
investigative techniques
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22. Investigative Productivity
PRODUCTIVITY
• Interest in the police field for some time
• All jobs have some standard of productivity
• Traditional evaluation

Number of cases assigned

Type of case assigned
• Continuous evaluation
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23. The Investigative Function:
The Responsibility of All Police Personnel
SPECIALIZATION NEED
• Criminals and their MOs
• Investigative techniques
• Leaving assigned shifts
• Heavy patrol workloads
• Increasing efficiency
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24. Interrelationships with Others—
Community Policing
COMMUNITY POLICING RELATIONSHIPS
• Uniformed patrol, dispatchers, prosecutors
• Physicians, coroners and medical examiners
• Forensic crime laboratories
• Citizens, victims, witnesses, media
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25. Major-Case Task Forces
COMBINED TASK FORCES
• Necessary for many crimes involving drugs, gangs and
terrorism
• Multidisciplinary approach
• Multijurisdictional investigation
• Metro crime teams
• Special investigation units
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26. Law Enforcement Resources
FEDERAL LAW ENFORCEMENT
• Numerous resources
• Aid local and state agencies
INTERPOL
• International Criminal Police Organization
• Computerized database is available to law enforcement
agencies worldwide
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27. Avoiding Civil Liability
CIVIL LIABILITY
• Effective policies and procedures clearly
communicated to all
• Thorough and continuous training
• Proper supervision and discipline
• Accurate, thorough police reports
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28. Summary
• Determine whether a crime has been committed
• Legally obtain sufficient information and evidence
• Locate and arrest the suspect
• Recover stolen property
• Present the best possible case to the prosecutor
• Cooperation and coordination of efforts are also
required outside the police department
• Criminal investigation is, indeed, a mutual effort
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