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Forensics Review SE1

Semester One Review for Forensics Science

What are the three fundamental principles of fingerprints? A fingerprint is an individual characteristic, remains unchanged during your lifetime, and has a characteristic ridge pattern that can be matched.
What are the three types of prints found at the crime scenes? Describe each one. Latent are invisible, plastic found in putty, dust, soft stuff, and visible (leaves blood, oil, etc…. on a surface with fingerprint.
What type of fingerprint would be left on skin? Latent
What are the three general classes and their subclasses for fingerprints? Arches are plain and tented. Loops are radial and ulnar, whorls include plain whorl, central pocket loop, double loop.
Which class is the most common fingerprint? pg. 54 __ulnar loop__
What method is the best to visualize a latent print left on glass? Dusting and lifting
What method is the best to visualize a latent print left on a matchbook? Superglue fuming
What is left behind by your finger when you touch a metal object? Sweat, oils, and amino acids
Is there a limit to the amount of time a fingerprint may last? No, it can last forever if preserved properly.
How many characteristics are sufficient to meet criteria of individuality? 8_ to _12___
What is AFIS? Automated Fingerprint Index System
What is glass made of? Silica and oxides
What are physical characteristics or properties of glass? Amorphous solid, brittle, hard, made of silica and oxides
Calculate the density of a piece of glass with a mass of 25g and a volume of 10mL. D=M/V D= 25g/10mL D = 2.5g/mL
What are the 6 types of glass and what is each used for? Sodalime-window glass, sodalead-fine glassware, silica- pyrex, borosilicate- chemical ware, tempered-car windows and plate glass doors, laminated- windshields.
Which glass type has the highest density? Sodalead
How do you collect glass at a crime scene? In a rigid container-like a box.
What can you tell me about the density of glass if it sinks in water? If it floats? Sinks = density is greater than 1 g/mL Floats = density is less than 1 g/mL
What type of evidence is glass? Class or individual depending on circumstances.
What is the immersion method used for and how does it work? Used for refractive index. Drop the glass into liquids with different refractive indexes and when it is invisible, it matches the refractive index of that liquid.
Explain what radial fractures and concentric fractures are on fractured glass. Radial fractures extend outward from the point of impact like the spokes of a wheel. Concentric fractures are circular.
How can we determine which side of the glass an impact came from? The hole on the exit side is wider.
Which form first: radial fractures or concentric fractures? Explain why. Radial fractures because they are from the initial impact or on the opposite side of the force.
Compared to where the force came from, which side of the glass do radial and concentric cracks form on? Explain. Radial fractures form from the initial impact or on the opposite side of the force whereas concentric form on the same side as the force.
How can you determine if a shot was perpendicular to a window, from the right, or from the left? Bullet hole would be oval shaped. If shooter is on the right, more glass will be missing on the left side of the bullet hole and vice versa.
How does the speed of impact affect the number of concentric fractures formed in the glass? High speed impacts produce fewer concentric fractures.
What is backscatter? Glass projected backwards and might be found on the suspect.
How does tempered glass differ from ordinary glass? What is it used for? Tempered and laminated both are heat treated and they break into small cubelike fractures: safety.
How does bulletproof glass differ from ordinary glass? Has 2 layers of thick glass and often a plastic layer inbetween.
Describe five different ways to distinguish between different pieces of glass evidence? Density, refractive index, fluorescence, color, thickness,markings.
How should glass evidence be collected, processed, and handled in a crime scene investigation? Different types of glass separated, labeled, and put in separate rigid containers like a box.
What is the responsibility of the crime scene officer at the crime scene? Assist those injured, isolate and protect the scene, detain witnesses A crime scene investigator is in charge of finding and collecting the evidence.
If a crime scene investigator takes photos of a crime scene, should he also take notes or make a sketch. Why or why not? Yes, so that there is a scale to go along with the photos.
What is direct evidence? Eyewitness testimony, also called prima facie.
What is indirect evidence? Physical evidence such as hair, fiber, glass, blood, DNA, etc…
Why do you think we collect over 50 head hairs from a control sample? So that we have a representative sample. Hairs from same head can have structural differences.
If a victim had dyed their hair and the dyed part was 2 cm from the root, how long had it been since the victim dyed their hair. 2 months. Hair grows 1 cm/ month.
Can they be more than 1 crime scene location? If yes, what or where? Where evidence can be located that will help to explain the events of the crime. Primary is where crime occurs. Secondary would be another location like a body dump.
What is the first step that an officer takes when approaching a crime scene? Assist those injured.
In addition to videotape, sketches may be helpful at a crime scene. Why? Gives details, scale, and a better overall layout of the scene.
What is a control? Controls are collected from where or who? Controls are samples taken from suspects or victims used to compare to the unknown evidence at a crime scene.
Why must a chain of custody be maintained for the evidence? So there is a record of where and who has touched the evidence. Without this, the evidence might not be admitted in court.
Is Crime scene evidence class or individual or can it be both? Why? It can be either depending on the circumstances and type of evidence found.
What can be determined from microscopic examination of hair? If it is human or animal.
What is the outer layer of the hair shaft? Describe it. It is the cuticle. Has scales. It is the protective covering.
What is the middle layer of the hair shaft? Describe it. The center of the hair is called the medulla. It can be a hollow tube, or filled with cells. In some people the medulla is absent, in others it is fragmented, or segmented, and in others it is continuous or even doubled.
What is the inner layer of the hair shaft? Describe it. The cortex. It contains melanin(color pigments) and gives the hair its shape.
Generally, a human hair can be distinguished from an animal hair by examining what part? The medulla.
Human hair can be characterized by having a medullary index of what? What types of medulla can humans have? Medulla index of <1/3______, Continuous, absent, fragmented.
Hair found at a crime scene is most likely to be in what phase of growth? Telogen
Nuclear DNA can be identified from what part of the hair? What does nuclear DNA show that can be used in court? __follicle or root_________A full DNA profile or fingerprint. Both parents.
An unidentified hair is examined . How do you know if it has been dyed? Bleached? Dyed - Cuticle and cortex will have color. Bleached - No color or a yellow tint.
What remains the hair’s most characteristic forensic feature? DNA in root or follicle.
The scales that make up the cuticle point to what part of the hair? The tip.
The cortex gives the hair its ______. The granules in the cortex are called ______and determine ______. The cortex gives the hair its __shape__. The granules in the cortex are called __melanin____and determine __color_____.
Name, describe, and (sketch) the five medulla patterns. Intermittent, fragmented, continuous, absent, and stacked.
The medullary index is determined by measuring the diameter of the Medulla divided by the diameter of the hair shaft. What is it for human hair? For animals? What is it for human hair?_<1/3 For animals_>1/2__
What is the main purpose for examining a hair found at the crime scene? To match it to a suspect, determine if it is animal or human, and eliminate victims and people at the crime scene as matches.
What is the approximate growth rate for hair per month? Cm:_1 cm / month___Inches: _1/2 in / month
What kind of DNA is in the hair shaft and what information does this give you? Mitochondrial DNA and it gives the mother.
What is Forensic Science? Science and application of science to matters of law. Forensic scientists oversee others collecting evidence at a crime scene, give expert testimony, and examine.
What governmental agencies have their own crime labs? ATF, DEA, FBI,US POSTAL SERVICE, US FISH AND WILDLIFE.
In Daubert vs. Dow, what must scientific evidence have in order to be admissible in Court? Theory or technique has been tested, science has been offered for peer review, rate of error is acceptable, method enjoys widespread acceptance, and opinion is relevant to the issue.
What is the name of the case that first determined what scientific evidence could be accepted in court? __1923 Frye vs. US________
Misdemeanors require how much time in prison/jail? No more than 1 year in jail.
What is testimonial evidence? Eyewitness testimony, statement made under oath, also called prima facie.
The reliability of eyewitness accounts depends on what factors? Nature of the crime, characteristics of the witness, manner in which information was retrieved, time between crime and testimony.
What is physical evidence? Give examples. Any object or material relevant to a crime, indirect evidence. Hair, fiber, glass, blood, DNA, fingerprints, drugs, documents, soil, bones, toolmarks, etc….
What makes evidence class evidence instead of individual? It cannot link a suspect to a crime with certainty but can exonerate individuals.
What does the Miranda Warning include? Rights for suspects.
What type of crime is homicide, rape, and arson? Felony
Define means, motive, and opportunity. Means- ability to do the crime. Motive-person has reason for the crime. Opportunity- person can be placed at the crime.
What is Locard’s exchange principle? Whenever two objects come into contact with each other, traces of each are exchanged.
What should be shown on a crime scene sketch? Scale, map, all evidence with distance measurements and reference points, legend.
What are the 3 classes of natural fibers. Name 5 natural fibers. Proteins, Cellulose or Vegetable, or Mineral. Cotton, silk, wool, cashmere, mohair.
What are synthetic fibers made of? Name 6 synthetic fibers. Synthetic fibers are made of fibers. Nylon, spandex, polyester, rayon, acetate, acrylic.
What are the 7 ways to test fibers for identification? Microscope, burning, thermal decomposition, chemical tests, density, refractive index, and fluorescence.
How should you collect clothing at a crime scene? Usually collected in paper bags, labeled, and have chain of custody.
How do you collect fibers found on skin or inanimate objects at a crime scene? Use tweezers or tape to lift fibers.
Are fibers class or individual evidence? Why? Class. Fibers are too common to be individual.
Created by: pam_brooks