CJ 210CRIMINAL

INVESTIGATON

The Investigator

• Responsibilities and Attributes;

Origins and trends

Responsibilities of the Investigator

• Determine whether a crime has been committed.• Verify jurisdiction.• Discover all facts, collect physical evidence and follow up

on clues.• Recover stolen property.• Identify the perpetrator or eliminate a suspect.• Locate and apprehend the perpetrator.• Aid the prosecution by providing evidence of guilt that is

admissible in court.• Testify effectively as a witness in court.

The Development of Investigative Methods.

• Wickersham Commission• Hans Gross (father of forensic investigation)• Francis Galton (fingerprint science)• Paul Ulenhuth (precipitin tests for blood species)• Calvin Goddard (comparison microscope)• Edmond Locard (first police lab – France)• Paul Kirk (criminalistics)

Physical Evidence

•Development, Interpretation & Investigative Value

Criminalistics Discipline

• Wet Chemistry• Instrumental Chemistry• Firearms & Toolmarks• Questioned Documents• Fingerprint • Photography• Lie Detection• Voice Spectroscopy

Identification v Identity

• Identification – the classification process by which an entity is placed in a pre defined, limited or restricted class.

• Identity – established when the physical is linked to the suspect.

Role of the Crime Lab

• Help establish elements of the crime.

• Link the crime scene to the victim or perpetrator.

• Reconstruct how the crime was committed.

• Induce an admission of confession.

• Protect the innocent.

• Provide expert testimony in court.

Clues that are sources of information

• Fingerprints• Firearms• Blood• Semen and other biological material ( DNA

profiling)• Document examinations• Trace evidence• Glass