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Transcript of Introduction to Forensic Science. Forensic Science Involves the application of scientific theory,...
Introduction to Forensic Science
Forensic Science
Involves the application of scientific theory, process, and techniques in legal matters.
Primary role of a forensic scientist is to analyze evidence gathered at a crime scene.
Science Disciplines Needed
Biology Physics Geology Anthropology Psychiatry Photography Toxicology Ballistics Odontology (in
forensics: examinationof bite marks and dental
identification of corpses) Engineering Chemistry
Computer technology Pathology
(investigation of asudden, unexplained
death) Environmental science Entomology (study of
insects, particularlydecomposers in forensics)
Palynology (study of pollen and spores)
Polygraphy (use of lie detectors)
Locard’s Exchange Principle
Edmond Locard was a pioneer in the field of forensic science.
He became known as “The Sherlock Holmes of France.”
In 1910, when he opened his forensic lab, he stated that whenever an individual comes in contact with a crime scene or victim, there will be an exchange of materials between them.
Two Types of Evidence
Testimonial evidence: prima facie evidence or direct evidence, a statement made by a competent witness under oath.
Physical evidence: real evidence; any object or material relevant to a crime.
Example of Physical Evidence
Hair, fibers, soil, glass, body fluids, fingerprints, pollen, bones, toxic substances, documents, firearms, ammunition, gunshot residues and impressions (bite marks, shoeprints, etc.)
Types of Physical Evidence
Individual: linked to a single source Examples:
fingerprints and footprints
Class: Material that can be linked to only a group of items with similar properties Examples: hair and
blood type
Two Forms of All Evidence
Both testimonial or physical evidence can be either direct or circumstantial evidence.
Direct evidence: links the suspect to the crime Examples: blood alcohol
content or possession of an illegal substance
Circumstantial evidence: points to a possible connection between the evidence and the suspect
Forensic Evidence Databases
The National Integrated Ballistics Information Network (NIBIN) allows the comparison of markings made by a firearm on bullets and cartridge casings.
The International Forensic Automotive Paint Data Query (PDQ) contains chemical and color information pertaining to original automotive paints.
SICAR (shoeprint image capture and retrieval) is a shoeprint database.
The Integrated Automated Fingerprint Identification System (IAFIS), a national fingerprint and criminal history system maintained by the FBI.
The Combined DNA Index System (CODIS) enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles.
The Crime Scene
Forensics begins at the scene of the crime.
Careful, objective, and scientific treatment of all evidence must occur.
If not, vital evidence may be overlooked, damaged, or contaminated; making it useless in a court of law.
Primary CSI Procedures
1. Interview2. Examine3. Photograph4. Sketch5. Process
1. Tag all evidence with a number.
2. Photograph it.3. Package it.4. Label it.
Notes
Police notes begin with your assignment to the case and continue to the end of the investigation.
Supplement all photos, sketches, and scale drawings.
Print with a smudge-proof blue or black ink.
Number and identify each page with your name, title, case number, and date.
Record the time an action was taken, information received, or event was observed.
Do not edit or erase. Line out the entry, initial, and rewrite.
Forensic Photography
No objects are removed until they have been photographed from all necessary angles.
Three ranges of picture documentation: Overview Intermediate Close-up (close and
perpendicular to the object.)
Photo Log Information
Assign each photo a number.
Describe photo contents.
Cite the time the photo was taken, the type of photo, and the distance to the focal point.
List the type of camera used and the height at which it was held.
Additional Photo Log
List the position of the camera or the angle of the camera shot.
List what lens was used; whether a flash was used; and whether digital or the type of film.
If film, note when new film is loaded.
Note all data on a photo sketch, as well as in your notes.
Crime Scene Sketches
Aerial view of the entire crime scene
Rough sketch vs. finished drawing
Elements of Sketching
Measurements Compass directions Essential items Scale or proportion Legend Title (case-file # and
offense) Projection Surveying methods
Rectangular (hypotenuse) or polar coordinates (length and angle.)
Projection Drawing
Looks like a box with all four sides flattened.