Do now: What type of information can an expert witness offer?

THE CASE: A fleet of U.S. naval vessels in heading due north into frigid Arctic waters when it comes under heavy enemy attack. One member of the flotilla sinks to the bottom and disappears from enemy radar screens. Although the captain and the entire crew went down with the ship, the rest of the fleet does not stop to look for survivors. THE MYSTERY: What type of ship sank to the bottom and how many crew members were killed? CLUES: The crew couldn’t survive for long in the cold Arctic waters. The crew couldn’t survive for long in the cold Arctic waters. No crew member was found in the water. The crew was prepared for what happened. The ship went hundreds of feet below the surface. The ship had sunk before. The ship continued its voyage as planned.

Properties of Physical Evidence Aim: How is physical evidence broken down in to different categories?

Physical Evidence Analysis  Class Characteristics –a. Describe the physical object and limit (but not eliminate) the likelihood that similar objects exist. –b. The greater the number of class characteristics that can be associated with a given object, the smaller the category within which the object can be placed. –c. The larger the number of class characteristics, the greater the value in an investigation. –d. Physical evidence with class characteristics may have more than one possible source.  Individual/Identification Characteristics of Physical Evidence –a. Establish a physical object's difference/uniqueness from all others within its group. –b. Establish the unique identity of an object or its source to the exclusion of all others.

Ballistic examinations

Mathematical Probability   The probability of any given occurrence at a specific place or time relates to the value of a piece of physical evidence. – –Example: The likelihood of two different people sharing an exact print (type, characteristics, spatial and planer relationship) is 1:10.   The less frequent the rate or probability of independent occurrences, the firmer the base of confidence becomes.   The greater the frequency of an occurrence, the less significance that can be attached to its evidentiary value.

  1969 yellow VW Beetle is observed in commission of a hit and run in   In 1969, yellow VW Beetles were common (popular car, limited color selection). The chances were greater that two yellow 1969 VW Beetles could exist in the same vicinity in 1969 than today. Therefore, this information may lack significance in   1969 yellow VW Beetle is observed in commission of a hit and run in   1969 yellow VW's (and VW's in general) are less common in   Therefore, the rate of occurrence of the presence of a yellow VW Beetle would be significantly less.   Thus, the odds (mathematical probability) would favor such a vehicle being the suspect vehicle if found in the vicinity/jurisdiction where the hit and run occurred. The presence of fresh damage would also impact the odds.

Major Groupings Of Physical Evidence  a. Physical evidence is any material, however microscopic, solid, liquid or gaseous, that may aid in the determination of the truth during the investigation of a crime.  b. Physical evidence capable of scientific analysis that is likely to be found at the scene of a crime falls into eight (8) major groups and one (1) miscellaneous group.

(1) Weapons - I.D. Knife wounds (2) Blood, saliva, and semen - I.D. (3) Latent impressions - I.D. (4) Shoe and tire impressions - I.D. (5) Tool Marks - I.D. (6) Questioned documents - Class to I.D. (7) Soil - Class (8) Glass – Class (9) Miscellaneous trace evidence such as hair, fibers, paint chips, and bomb residue - Class