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

THE CASE:THE CASE:A fleet of U.S. naval vessels in heading due north A fleet of U.S. naval vessels in heading due north

into frigid Arctic waters when it comes under into frigid Arctic waters when it comes under heavy enemy attack. One member of the flotilla heavy enemy attack. One member of the flotilla sinks to the bottom and disappears from enemy sinks to the bottom and disappears from enemy radar screens. Although the captain and the radar screens. Although the captain and the entire crew went down with the ship, the rest of entire crew went down with the ship, the rest of the fleet does not stop to look for survivors.the fleet does not stop to look for survivors.

THE MYSTERY:THE MYSTERY:What type of ship sank to the bottom and how What type of ship sank to the bottom and how many crew members were killed?many crew members were killed?

CLUES:CLUES: The crew couldn’t survive for long in the cold The crew couldn’t survive for long in the cold Arctic waters.Arctic waters.No crew member was found in the water.No crew member was found in the water.The crew was prepared for what happened.The crew was prepared for what happened.

The ship went hundreds of feet below the surface.The ship went hundreds of feet below the surface.The ship had sunk before.The ship had sunk before.The ship continued its voyage as planned. The ship continued its voyage as planned.

Properties of Properties of Physical EvidencePhysical Evidence

Aim:Aim: How is physical How is physical evidence broken down evidence broken down

in to different in to different categories?categories?

Physical Evidence AnalysisPhysical Evidence Analysis Class CharacteristicsClass Characteristics

– a. Describe the physical object and limit (but not a. Describe the physical object and limit (but not eliminate) the likelihood that similar objects exist.eliminate) the likelihood that similar objects exist.

– b. The greater the number of class characteristics b. The greater the number of class characteristics that can be associated with a given object, the that can be associated with a given object, the smaller the category within which the object can smaller the category within which the object can be placed.be placed.

– c. The larger the number of class characteristics, c. The larger the number of class characteristics, the greater the value in an investigation.the greater the value in an investigation.

– d. Physical evidence with class characteristics d. Physical evidence with class characteristics may have more than one possible source.may have more than one possible source.

Individual/Identification Characteristics of Individual/Identification Characteristics of Physical EvidencePhysical Evidence– a. Establish a physical object's a. Establish a physical object's

difference/uniqueness from all others within its difference/uniqueness from all others within its group.group.

– b. Establish the unique identity of an object or its b. Establish the unique identity of an object or its source to the exclusion of all others.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  1969.

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.

1969 yellow VW Beetle is observed in commission of a hit and run in 2001.

1969 yellow VW's (and VW's in general) are less common in 2001.

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 Major Groupings Of Physical EvidenceEvidence

a. Physical evidence is any a. Physical evidence is any material, however microscopic, material, however microscopic, solid, liquid or gaseous, that may solid, liquid or gaseous, that may aid in the determination of the aid in the determination of the truth during the investigation of truth during the investigation of a crime.a crime.

b. Physical evidence capable of b. Physical evidence capable of scientific analysis that is likely to scientific analysis that is likely to be found at the scene of a crime be found at the scene of a crime falls into eight (8) major groups falls into eight (8) major groups and one (1) miscellaneous group.and one (1) miscellaneous group.

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

hair, fibers, paint chips, and  bomb hair, fibers, paint chips, and  bomb residue - Classresidue - Class