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.