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What are the three fundamental principles of fingerprints?
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What are the three types of prints found at the crime scenes? Describe each one.
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Forensics Review SE1
Semester One Review for Forensics Science
| Question | Answer |
|---|---|
| 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
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