Forensic Science Exam 1

Chapter 1:

• CSI shows are 90% fiction and not good reflections of actual crime investigations

Application of the sciences to law:

American Academy of forensic sciences:

• Largest forensic science organization in the world 

• Promotes integrity, education, research in forensic science

History:

• Can be traced back to 16th century europe in the gathering of information on the cause and manner of death - heavy dependence on eye witnesses

• 18th century started collecting evidence to solve crimes - looking to science

Mathieu Orfila:

• Father of forensic toxicology

• 1814 - treatise on detection of poisons and their effects on animals

Alphonse bertillon:

• Devised the first scientific system of personal identification, using body measurements known as anthropometry in 1879

Francis Galton:

• Conducted the first definitive study

Leone Lattes:

• Developed a procedure to determine blood type for dried bloodstains

• Today we recognize these blood types as A, B, AB and O. His technique was quickly applied to criminal investigations.

Calvin Goddard: 

• Used a comparison microscope to determine if a bullet was fired from a specific gun

• Published study of “tool marks” on bullets

Albert Osborn:

• Developed the fundamental principles of document examination. His book is still used today for document examiners. 

Han Gross:

• Wrote the first treatise describing the application of scientific principles to the field of criminal investigation. 

• Was a public prosecutor and judge in Austria spending many years studying and developing principles leading to his book in english, “criminal investigation”

Edmond Locard: (going to be tested on this for sure)****

• Whenever two objects come into contact with one another there is exchange of material between them

  • This concept is the locard exchange principle-basis for transfer of evidence

Alexander Gettler:

• The first forensic chemist to be employed in this capacity by a US city (ny)

• Has been described by peers as “the father of forensic toxicology in America” 

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Crime laboratories:

4 major federal crime labs:

• FBI

• DEA (drug enforcement administration)
  ATF (bureau of alcohol, tobacco, firearms and explosives

• US postal inspection service

Standard:

• Physical science biology

• Firearms

• Documents

• Photography

Optional:

• Toxicology

• Fingerprints

• Digital evidence

Forensic scientist:

• The forensic scientist applies their scientific knowledge to analyzing of evidence

• Courtroom testimony is a huge part of the forensic scientist duties

• They must persuade the jury to accept their conclusions or results of the analysis

Two types of physical evidence:

• Individual characteristics.

  • A piece of evidence that is unique and can be identified to the exclusion of all others. 

  • Fingerprints

  • DNA

Class Characteristics:
- features shared by all members of a group or class

- footprints

Physical evidence:

• Cannot lie, forget, be mistaken when properly identified, collected and preserved

• Is demonstrable

• Is not dependent on the presence of witnesses

• is , in some instances, the only way to establish the elements of the crime

• Physical evidence integrity comes from strict guidelines that insure careful and systematic collection, organization and analysis of info known as the “scientific method”

Who committed the crime? Investigator formulates a hypothesis

What? Testing of the hypothesis through 

Cases:

Frye v. US - set the guideline that to be admissible the evidence must have been processed using a procedure or techniques that is “generally accepted” by scientific community in the field it belongs

• As new techniques become available they must be reviewed by other scientists to become “generally accepted” by the scientific community

Daubert v merrell dow pharmaceuticals:

1993 landmark ruling by the supreme court that evidence deemed “generally accepted” by the Frye standard is not absolute

• This ruling assigns the trial court judge

Daubert guidelines;

• Has the scientific technique been tested has it been subject to peer review and publication

• The techniques potential rate of error

• Standards controlling the techniques operation

• Has the method attracted widespread acceptance within a relevant scientific community

Expert testimony:

• Expert testimony can be a factor in determining a person’s guilt or innocence. So the forensic scientist may be required to testify about their methods, results and conclusions at the trial

Crime Scene Lecture:

Defining the crime scene:

• Location according to criminal

  • Primary vs. secondary

• Size

  • Macro vs. micro

• Type 

  • Homicide, robbery, etc. 

• Condition

  • Organized vs. disorganized

• Physical location

  • Indoors, outdoors, vehicle, etc. 

• Associated criminal behavior

  • Passive vs. active (more crime in certain areas)

Uses and info from physical evidence:

• Linkage of persons, scenes, or objects

  • Locard's exchange principle

• Provide investigative leads

  • Direct and indirect leads

• Info on the corpus delicti or modus operandi

Digital imaging:

Advantages:

• Instant access

• Integration

• No film processing

Disadvantages:

• Court admissibility

Crime Scenes continued…

Collection and preservation: 

• Primary and secondary container

• Sealed

  • Completely cover opening

  • Initialed, time and dated

• Labeled

  • Collector and date/time/location

Evidence seal must always be initialed and dated

Evidence form:

• Every piece of evidence must be listed on the evidence form

• As each piece of evidence is exchanged between officers and examiners

Crime scene reconstruction:

• Determining or eliminating events

• Involves:

  • Interpretation of evidence 

  • Laboratory testing

Physical Evidence:

Any object that can establish a link between the victim and the perpetrator

Crack vs. Cocaine:

• Cocaine is a salt 

• Crack is cheaper and more popular with low income households

• Epidemic of crack in the 80s

Identification: 

• Determine the physical or chemical identity with as near absolute certainty as existing analytical techniques will permit. 

Explosives: residue from the explosion and unexploded bomb were linked together and the powder linked back to the powder manufacturer. 

Alternate Light Source (ALS)

Reconstruction: Blood Stain Pattern (Chapter 4)

Impact spatter: occurs when an object impacts a source of blood

Forward spatter: is projected outward and away from the source

Back spatter: also known as blow-back spatter, is projected backward from the source

If the bullet does not exit the body, a gunshot produces only back spatter***

Using droplet size to classify impact patterns by velocity

Angle of impact equation:

Sin A = width of blood stain/length of blood stain

Sin A = 1.5cm/3.0 cm = 0.50 

Sin of 1.50 = 30 °

Low velocity spatter: drops with diameters of 4 mm or more normally produced by an applied force of up to 5 ft/sec

Medium velocity: drops with diameters from 1-4 mm with an applied force of 5 to 25 ft/sec

High velocity: drops with diameters of less than 1 mm from an applied force of 100 ft/sec or faster

At least two blows for sure if there is blood splatter when it comes to stabbing**

Arterial spray spatter is caused by an injury to the heart, or main artery and is generally brighter in color

Expirated bloodstain pattern: forcefully expelled blood from the nose or mouth that has accumulated in the lungs, sinuses, and airway passages of the victim as a result of trauma

Area of convergence: the point on a two-dimensional plane from which the drops in an impact pattern originated

Area of origin: an impact bloodstain pattern is the area in a three dimensional space from which the blood was projected. 

Flow patterns are made by drops or large amounts of blood flowing by the pull of gravity

• Surface texture is the most important in the interpretation of bloodstain patterns