1. Criminal Investigation: An Overview
Chapter 1
Criminal Investigation: An Overview

2. Criminal Investigation Defined
An investigation is a patient, step-by step inquiry or observation, a careful examination, a recording of evidence or a legal inquiry.
Investigate is derived from the Latin word investigare, meaning “to track or trace.”

3. Crimes Defined I
A crime is an act in violation of penal law and an offense against the state.
A felony is a serious crime, graver than a misdemeanor, generally punishable by death or imprisonment of more than one year in a penitentiary.

4. Crimes Defined II
A misdemeanor is a crime or offense that is less serious than a felony and punishable by fine or imprisonment of up to one year in an institution other than a penitentiary.
A criminal statute is a legislative act relating to a crime and its punishment.
An ordinance is an act of the legislative body of a municipality or county relating to all the rules governing it, including misdemeanors.

5. Goals of Criminal Investigation
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.

6. Examples of Trace Evidence
Fingerprints
Small particles of glass
Dirt
Footprints
Body hairs
Clothing fiber

7. Successful Investigation
Follow a logical sequence
Legally obtain all physical evidence
Effectively interview all witnesses
Legally and effectively interrogate all suspects
Thoroughly develop all leads
Record and report all details of the case

8. Always Remember
Determining the truth is more important than obtaining a conviction or closing a case.

9. Functions Investigators Perform
Obtain information from witnesses and suspects
Identify suspects
Conduct raids, surveillances, stakeouts, and undercover assignments
Testify in court
Provide emergency assistance
Secure the crime scene
Photograph, videotape, and sketch
Take notes and write reports
Search for, obtain, and process physical evidence

10. Facts, Inferences, and Opinions
Fact: an action, an event, a circumstance, or an actual thing done.
Inference: a process of reasoning by which a fact may be deduced.
Opinion: a personal belief.

11. Preliminary Investigation: Basic Considerations I
Initial response
Point of arrival
Setting priorities
Handle emergencies first
Secure the scene
Investigate

12. Preliminary Investigation: Basic Considerations II
Handling emergency situations
Suspect near or at the scene
Suspect recently fled
Person seriously injured
Dead body
Protecting the crime scene

13. Responsibilities of Preliminary Investigation
Measuring, photographing, videotaping, and sketching a scene
Searching for evidence
Identifying, collecting, examining, and processing physical evidence
Questioning victims, witnesses, and suspects
Recording all statements and observations in notes

14. Crime Analysis
Crime analysis is the systematic gathering, evaluation, and analysis of information on individuals and/or activities suspected of being, or known to be, criminal in nature.

15. Facts in Support of Crime Mapping
Two-thirds of all crime occurs indoors, not visible to the police.
Most serious crimes are perpetrated within a short time frame.
Patrol officers intercept less than 1 percent of street crimes.
The same 10 percent of locations within a jurisdiction generate approximately 65 percent of that jurisdiction’s total calls for service.

16. Forensic Science/Criminalistics
The application of physical and biological sciences and technology to the scientific examination of physical evidence.

17. Basic Needs of Victims Victims need to feel safe
Victims need to express their emotions
Victims need to know “what comes next” after their victimization

18. Avoiding Civil Liability Against Police Officers
Effective policies and procedures clearly communicated to all.
Thorough and continuous training.
Proper supervision and discipline.
Accurate, thorough police reports.