Observations/ evidence
Why by eyewitness accounts always be accurate?
How do they vary from person to person?
1. We tend to be unaware of our surroundings.
We are preoccupied (driving, talking, texting)
We may be upset, afraid, or anxious.
2. Brief sightings
Interest of the situation
Distractions
Stress
Prejudices or bias (race, gender, age)
When comparing a sample writing to a suspect document, the age difference between the documents should be no more than…
2-3 years old
If an autopsy determined that a person died of asphyxiation, how could it be determined if it was a homicide or Suicide?
The hyoid bone can determine whether a body was strangled or hung.
What is entomology and how is it used in forensic science?
The study of insects and other arthropods
Forensic entomology can help estimate PMI
What are the different types of arches, whorls, and loops?
Arches: plain and tented
Loops: ulnar and radial
whorls: plain, central pocket, double loop, and accidental
What did the innocent project find that most faulty convictions were based on?
What percentage of the wrongful convictions did this affect?
1. Inaccurate eyewitness accounts
2. 87%
What factors affect handwriting? (Name 5)
What are the 12 characteristics of handwriting? (Name 3)
1. Mood
Writing instrument
Use of alcohol or drugs
Medication
Age
2. Line quality
Spacing
Size consistency
Continuous
Connecting letters
Letters complete
Cursive and printed letters
Pen pressure
Slant
Line habits
Fancy curls or loops
Placement of crosses and dots
Define: Cause of death, manner of death, and mechanism of death.
Cause: the reason someone dies
Manor: the way in which a person dies
Mechanism: the specific change in the body that brought about the cessation of life
How long is the life cycle of a blowfly?
How long does it take for the eggs to hatch?
1. 25 days
2. 24 hours
What are the percentages if each fingerprint pattern?
Arches: 5%
Loops: 65%
Whorls: 30%
Why do forensic scientists have to be a good communicator by giving expert testimony in a court of law?
To convince the jury that the analysis of evidence is accurate and reliable.
What type of paper used to make currency?
How is regular paper detected?
1. Special paper made of plant fibers such as cotton and linen
2. Starch indicator/iodine (amber turns blu/black when starch is detected)
What is autolysis?
Cell self digestion
Damaged cell triggers autolysis and enzymes are released inside the cell that break down contents and ruptures in the cell membrane
What is the rule of thumb?
Dead less than 3 hours: body warm and limp
Dead 3-8 hours: body warm and stiff
Dead 8-36 hours: body cold and stiff
Dead more than 36 hours: body cold and limp
what are the 3 types of fingerprints?
Patent: visible fingerprints that were coated when they touched a surface and transferred the print
Latent: fingerprints that aren’t visible to the unaided eye caused by the transfer of oils
plastic: fingerprints in indentations in a soft material
Define: Direct evidence, Trace evidence, class evidence, and individual evidence.
Direct evidence: firsthand observations
Trace evidence: circumstantial/indirect evidence: evidence that provides a link between a crime scene and suspect
Class evidence: narrows suspects to a group of people
Individual evidence: narrows suspects to a single person
What did the US Supreme Court case United States vs Mara decide?
Taking a handwriting sample did not constitute an unreasonable search and seizure of a person and it did not violate the 4th amendment.
What is livor mortis? (Give timeline)
What is rigor mortis, what factors affect it and how? (Give timeline)
1. The settling of blood (Color of body)
Less than two hours: none
2-8 hours: temporary (blanching)
more than 8 hours: permanent
2. Stiffness of muscles
less than 2 hours: no rigor
2-15 hours: rigor starts
15 hours: peak rigor
15-36 hours: loss of rigor
more than 36 hours: no rigor
Factors that quickens rigor: warm, exercise, skinny, naked
Factors that slow rigor: cold, at rest, obese, clothed/covered
What is algor mortis?
How do you calculate it?
What factors affect it and how?
1. The speed at which the body loses heat
2. Subtract from 37, and then divide by .78
If the body temperature is under 27.64, subtract from 27.64, divide by .39, and then add 12 hours
3. Factors that speed it up: cold or shady, young child or elderly, windy, illness, blood loss, small or frail, naked
Factors that slow it down: sunny, obese, clothed or covered, sick, enclosed area
What is minutiae and what are the different types?
Ridge characteristics
1. Ridge ending
2. Fork (bifurcation)
3. Island ridge
4. dot
5. Bridge
6. Hook (spur)
7. Enclosure (eye)
8. Double bifurcation
9. Delta
10. Trifurcation
What are the 7 S’s of a crime scene?
1. Secure the crime scene
2. Separate witnesses
3. Scan the crime scene
4. See the crime scene
5. Sketch the crime scene
6. Search for evidence
7. Secure and collect evidence
What is Paper Chromatography, how does it work, and what is it used for?
What equation is used?
1. Paper Chromatography separates the different colors in ink.
The more soluble the further up the paper the pigment travels. If the ink if made up of multiple different colors, the paper will show different colors. If the ink is pure, there is no separation.
This is used to trace back what company used the ink or detect forgery additions.
2. Rf=dt/dw
Rf: retention factor
Dt: distance the pigment traveled
Dw: distance the water traveled
1. Fresh (initial)
2. Bloating (putrefaction)
3. Active decay (black putrefaction)
4. Advanced decay
5. Dry (skeletal)
How does the eyes change after death?
Corneal clouding: surface of the eye dries out (cloudy film that covers eye)
Tache noir: brown corneal surface from mucus of the eye and debris from the environment forming two yellow triangles on the sclera on each eye
Ocular fluid: fluid within the eye, after death potassium is released into the ocular fluid
How, where, and when are ridges formed?
During the 10th week of gestation, fingerprints develop in the Basal layer of the skin and are influenced by: bone growth, pressures in the womb, and contact with amniotic fluid