Evidence

Civil vs. Criminal LawCIVIL LAW CRIMINAL LAW filed by a private party.

o a corporationo an individual person

Penalty: a guilty defendant pays the plaintiff for losses caused by their actions.

o no incarceration

filed by the government

Penalty: a guilty defendant is punished by

o incarceration (in jail/prison)o fine paid to the governmento execution (death penalty)

Crimes are divided into 2 classes: o misdemeanors - less than 1 year incarcerationo felonies - sentence of 1+ year

Direct Evidence = Eyewitness Testimony◦ “I saw her do it!” “I heard him say it!”◦ Eyewitness testimony is nonphysical evidence.

Indirect Evidence = Physical Evidence◦ “The victim’s hair was found on the defendant’s

clothing.”◦ “The defendant’s DNA was found at the crime

scene.” Evidence generated by criminal activity is real

evidence.

Two Types of Evidence in Court

Pros:◦ Easy to understand◦ It appeals to our common sense

Cons:◦ Witnesses can be wrong◦ Witnesses can lie◦ Witnesses can be biased

Direct Evidence

Cons:◦ Science (and scientists) can be hard for juries

(and even judges) to understand◦ If evidence isn’t collected or tested properly, the

conclusions drawn from it can be wrong◦ If there is some evidence that isn’t collected or

some test that isn’t performed, then the conclusions drawn from what was collected can be wrong

Indirect Evidence

PRO: Physical Evidence can be analyzed scientifically◦ Science is not biased◦ Science is logical, not emotional◦ Science is repeatable and can be demonstrated to

work again and again◦ Conclusions drawn from good science can be

trusted

Indirect Evidence

Identification:◦ Attempts to determine the identity of the

evidence (especially if unknown evidence) to as high a degree of certainty as possible Examples:

What did this hair come from? When the fire spread, was the accelerant kerosene or

gasoline? Is this a blood stain? What is this unknown fiber

How Physical Evidence Is Used

Comparison:◦ Determines if two objects (the evidence and a

standard) have a common origin (are made of the same materials, come from the same factory, were both at the crime scene, were both fired from the same weapon, etc)

How Physical Evidence Is Used

Evidence that is not unique Not used to identify a person An examiner can only figure out if the evidence

being analyzed belongs to a particular group◦ Examples:

Blood Type Car Make and Model Hair Color Clothing fibers Soils Illegal drugs

Class Evidence

Evidence that connects to a specific individual

Unique The evidence identifies the individual. This piece of evidence can’t be linked to

anyone else.◦ Examples:

DNA Custom Paint on a Car Fingerprints

Individual Evidence

ORGANIZATION of aCRIME LABORATORY

Drugs◦ Identify the type of drugs

Glass◦ Particles being transferred from suspect to the

crime scene or the crime scene to the suspect.◦ Glass containing bullet holes or other projectiles

Explosives◦ Identifies the explosive◦ Examines the charred remains of the explosion.

Physical Science Unit

Impressions◦ Markings from:

Tires Shoes Fabric Teeth

Petroleum products◦ Accelerants in arson◦ Grease, oils found at the crime scene

Plastic bags◦ Associated with homicides and drug cases◦ Identified with similar bags in the possession of a

suspect. Plastics, rubbers and other polymers

◦ composition may be unique to a manufacturer. Powder residue

◦ Indicates firearm use.

Soil and Minerals◦ link a person to a location

Vehicle lights◦ Lights at accidents are checked to see if they

were being used Fingerprints

◦ Examination of visible, latent or plastic prints. Serial Numbers

◦ Identifies stolen property◦ Filed down or altered numbers can be recovered

Blood, Semen, Saliva:◦ Identifies individuals who may have been present

at a crime scene. Wood and vegetative matter

◦ Wood, sawdust, shaving, leaves, flowers can link a person to an area.

Fibers◦ Natural or synthetic fibers that are transferred at

the crime scene.

Biology Unit

Firearms & ammunition◦ Weapons◦ Ammunition◦ Casings◦ Bullet holes

Tool Marks◦ scrapes and scratches on a surface will match the

tool that made it.

Firearms Unit

Documents:◦ Handwriting and typing ◦ checks for authenticity of author◦ Inks and paper◦ checks for composition and age.◦ Related items, charred, burned or altered

documents.

Document Examination Unit

Organs & Physiological fluids◦ Detects drugs and poisons◦ Metabolic disorders

Toxicology Unit

Evidence Collection

Cross contamination with another vehicle or person can transfer the following:◦ tissues◦ blood◦ hair◦ soil◦ paint ◦ broken glass◦ fabric impressions

Evidence is located by:◦ Vacuums◦ Scraping◦ Visual examination of the area

Specific Concerns for Vehicles

Evidence from the Scene:◦ Broken glass◦ Blood◦ Weapons◦ Rope, tape◦ Victims clothing◦ Fingernail scrapings◦ Head and pubic hairs◦ Blood◦ Vaginal, anal and oral swabs◦ Recovered bullets

Specific Concerns forRape or Assault

Each item must be packaged separately◦ Plastic pill bottles are useful for:

Hairs Glass Fibers Other types of trace or small evidence

◦ Manilla envelopes, glass vial or pill boxes are also useful

◦ Specialized Containers are required for: Bloody Clothes: Need to be placed in paper bags. Arson Residue: Glass or metals containers with sealed

lids.

Packaging Evidence