Forensic Chapter 3

Physical Evidence

Encompasses any objects that establish whether a crime has been committed, linking a crime to its victim or perpetrator.

Identification

Determination of the physical or chemical identity of a substance with near absolute certainty.

Comparison Analysis

Subjects a suspect specimen and a standard/reference specimen to the same tests to determine if they share a common origin.

Individual Characteristics

Evidence that can be associated with a common source with an extremely high degree of probability.

Class Characteristics

Evidence associated only with a group and not a specific source.

Common Types of Physical Evidence

Includes blood, documents, drugs, explosives, fingerprints, paint, soil, and tool marks.

Probabilistic Role in Evidence

Probability helps in determining the origins of specimens but can be complex in forensic analyses.

Forensic Databases

Systems like IAFIS, CODIS, and NIBIN used for comparing fingerprints, DNA profiles, and firearm markings.

Natural Variations

Infinite natural differences in objects that complicate forensic comparisons.

Evidential Variations

Differences in evidence that arise from the specifics of a crime scene, as opposed to natural variations.

Sophisticated Analytical Techniques

Advanced methods used in forensic science that allow for precise identification and comparison.

Exoneration through Evidence

Physical evidence collected at a crime scene may lead to exclusion of a suspect if found different from standard samples.

Tattoo Evidence

Can also serve as a form of physical evidence linking individuals to crimes, albeit less common.

Fingerprint Matching

Involves comparing ridge patterns to determine individual characteristics, establishing a high probability of a common source.

Statistical Databases for Class Evidence

Forensic scientists work to create and update databases that help evaluate the significance of class physical evidence.