What are the 5 steps in crime scene investigation?
Secure crime scene
Observe crime scene
Document crime scene
Search crime scene
Collection & preservation of evidence
Who should certify that the body is "dead"?
What does observing a crime scene involve?
Initial walk through
Plan of action
What are the 4 search patterns for crime scenes?
Grid, quadrant or zone, spiral, line or strip
How do you decide what pattern to use?
Based on size/location of crime scene and number of investigators.
How do you package evidence at a crime scene?
Individually, allow wet objects to dry
What evidence cannot be packaged immediately? Why?
Wet evidence because it could be destroyed by mold or mildew
Taking body measurements as a way to distinguish one individual from another
What two scientists were known for devising experimentation for blood types?
Karl Landsteiner and Leon Lattes
Who was responsible for courts acceptance of documents as scientific evidence?
Determine skeletal remains through dental records
Determine whether drugs are in a human body
Determine if bones are human or animal
Determine competency of a suspect to stand trial
Determine time of death using insects
Investigate structural failure and investigate accidents
Perform autopsies to determine death
Recover data from digital media
Analyze and interpret physical evidence
Analyze ink, paper, toner in questioned documents
What is a misdemeanor?
What is a felony?
What court case in 1923 set the "general acceptance" of scientific evidence?
Frye vs. United States
What are the roles of an expert witness?
Establish credibility through credentials, background experience.
Render an opinion about the evidence.
What do forensic scientists use physical evidence for?
Identification and comparison.
What is identification used for?
To determine physical or chemical identity
What is comparison analysis used for?
To determine whether a common origin exists
What is the difference between individual characteristics and class characteristics?
Exact identity compared to a common origin
What are 2 examples of physical properties?
Density, color, texture, odor
What are 2 examples of chemical properties?
What is the SI unit for length?
What is the SI unit for volume?
What is the SI unit for mass?
What does kilo mean?
What does deci mean?
What does hecta mean?
What does milli mean?
What does centi mean?
What does deca mean?
What is the formula to calculate density?
What is refraction?
Bending of light as it moves from one medium to another
Example- air to water
What is the range for pH?
What can fracture patterns tell an investigator?
Sequence of events
Direction of impact
High or low velocity impact
What are the types of fracture patterns of glass?
Radial and concentric
If the refractive index of glass matches that of a liquid, what will you see when ou put the glass sample inside the liquid?
The glass will disappear
What are natural fibers?
Fibers made from animals or plants
What are some examples of natural fibers?
Cotton, wool, silk, hemp
What are synthetic fibers and what would be an example?
Manmade or altered fibers
Acetate, rayon, polyester
What type of fibers contain proteins?
What three fibers dissolve in formic acid?
Nylon, silk, acetate
When performing the sulfur test, what color precipitate should show a positive outcome?
Black or dark grey
What is the only fabric to dissolve in acetone?
What are examples of mineral fibers?
Asbestos, rock wool, fiberglass
What are examples of cellulose fibers?
Cotton, rayon, cullulose acetate
What is the difference between hydrophilic and hydrophobic?
How should you collect fiber evidence?
Make tape lifts, bag evidence individually, removed fibers should be folded into a sheet of paper and stored in a paper bag
How often does hair grow?
What are the 3 layers of hair?
Cuticle, cortex, medulla
Which layer has pigment granules?
Which layer is resistant to chemical decomposition?
How can the medulla be classified?
Interrupted, fragmented, continous, stacked, absent
What type of medullas do animals usually have?
Stacked, continuous or interrupted
What type of medullas do humans usually have?
Continuous, fragmented or absent
What are th 3 stages of growth?
Anagen, catagen, telogen
How long does each stage of growth last?
Anagen- up to 5 years
Catagen- 2-3 weeks
Telogen- 2-6 months
Can scientists determine body area that hair came from comparison?
What is the best stage for DNA comparison of hair?
If there is no nuclear DNA present, what type do scientists use?
When taking reference samples from the head, how many hairs do you need?
50 full length hairs