Question: What happens to a light beam that

> List two factors that make it difficult for criminalists to compare glass samples.

> What two models do scientists use to explain the nature of light? Under what conditions does each model best describe the behavior of light?

> What is color? What determines the color of an opaque object?

> Define intensive property and name two intensive properties of matter.

> Explain how a prism disperses white light into its constituent colors.

> What is the difference between a crystalline solid and an amorphous solid? How does this difference affect the refractive index of each of these types of solid?

> Define the terms refraction and refractive index.

> What is density? How does heat affect the density of gases and liquids?

> What is a phase and how can two different phases be distinguished from one another?

> Define sublimation. What happens to the attractive forces between molecules of a substance that undergo sublimation?

> Criminalist Pete Evett is collecting fiber evidence from a murder scene. He notices fibers on the victim’s shirt and trousers, so he places both of these items of clothing in a plastic bag. He also sees fibers on a sheet near the victim, so he balls up t

> Define the terms physical property and chemical property.

> What is the Greiss test and what two pieces of information can it provide to an investigator?

> List three characteristics of a bullet hole that indicate that the shot was fired at extremely close range.

> What evidence does an investigator study to make a distance determination? How can test-firing a suspect weapon help the investigator make a distance determination?

> What is distance determination? Describe two situations in which distance determination can establish the facts of a shooting incident.

> Why does a firearms examiner test-fire bullets from a suspect barrel?

> Besides the barrel, what parts of a firearm may leave distinctive markings on a shell cartridge?

> List two reasons why striations on bullets fired from the same gun may vary slightly.

> What kinds of impression evidence might a forensic odontologist be asked to analyze? How might this help identify a suspect?

> Describe how a firearms examiner compares two bullets. What characteristic does an examiner most often use to identify bullets and why?

> Following are descriptions of several hairs; based on these descriptions, indicate the likely race of the person from whom the hair originated: a. Evenly distributed, fine pigmentation b. Continuous medullation c. Dense, uneven pigmentation d. Wavy with

> A Timeline of Forensic Science The following images depict different types of evidence or techniques for analyzing evidence. Place the images in order pertaining to the time in history (least recent to most recent) at which each type of evidence or techn

> What is the first thing the investigator does before handling or moving any impression at a crime scene? Why is this considered merely a backup or precautionary procedure?

> What techniques does an investigator use to analyze tool marks that cannot be removed from a crime scene? What is the disadvantage of this technique?

> Name two types of marks that impart individuality to a tool and explain how the marks are made.

> What is the investigator’s primary concern when collecting and handling bullets and cartridge cases? Why must the investigator exercise extreme caution when removing a bullet lodged in a wall or other object?

> What characteristics of a suspect firearm should an investigator record before unloading it? Why should the investigator number the chambers and cartridges when unloading a suspect weapon?

> Why would an investigator not pick up a weapon by its barrel with a pencil or stick in order to protect latent fingerprints? How should suspect firearms be handled in such a situation?

> Describe how a criminalist restores an obliterated serial number on a weapon.

> Why does analysis of primer residue from a suspect’s hands produce a low rate of positive results? Why is such analysis typically ineffective in locating primer residue from a . 22-caliber gun?

> What evidence do investigators look for when trying to determine whether a suspect has fired a handgun? Where is such evidence typically found and why?

> How is shot pattern used to make a distance determination for shotgun blasts? What factors other than distance to target can affect the distance determination?

> A criminalist studying a dyed sample hair notices that the dyed color ends about 1.5 centimeters from the tip of the hair. Approximately how many weeks before the examination was the hair dyed? Explain your answer.

> List three class characteristics of a gun barrel.

> How did the comparison microscope make possible modern firearms examination?

> Briefly describe how a comparison microscope works and what it is used for.

> Why might an examiner choose a microscope with a lesser magnification to study a specimen?

> What does numerical aperture (N.A.) measure? What is the difference between a lens with N.A. 1.0 and one with N.A. 0.5?

> What is the difference between a real image and a virtual image?

> How does one calculate the magnification power of a compound microscope?

> What is vertical illumination and under what conditions would a forensic scientist use it to examine a sample? Why is it superior to transmitted illumination under such conditions?

> Why does a compound microscope produce greater magnification than a magnifying glass? How does the eyepiece lens contribute to magnification?

> How can a scanning electron microscope be used to determine whether a suspect has recently fired a gun?

> Indicate the phase of growth of each of the following hairs: a. The root is club shaped b. The hair has a follicular tag c. The root bulb is flame shaped d. The root is elongated

> How can a scanning electron microscope be used to identify the elements present in a specimen?

> What is the basic difference between a scanning electron microscope and the other microscopes used in the crime laboratory?

> Explain how the infrared micro-spectrophotometer determines the identity of a specimen. What type of physical evidence is the micro-spectrophotometer typically used to analyze?

> What is the main advantage of the micro-spectrophotometer?

> What is the most widely used microscope in the crime laboratory? What features make it particularly suited for examination of physical evidence?

> List two unique characteristics of the stereoscopic microscope.

> How does a magnifying glass enlarge objects viewed through it?

> Which module is responsible for saving all of the raw data produced by feature extraction and putting it into a simple and easy to read format for the system?

> What biometric system process or module performs most of the “heavy lifting” for the system?

> The accompanying figure depicts stress marks on the edge of a glass fracture caused by the application of force. If this is a radial fracture, from which side of the glass (left or right) was the force applied? From which side was force applied if it is

> What is the first process that each biometric system must perform? What does it consist of?

> What are some of the specific stages that comprise gait recognition as a form of behavioral biometrics?

> What is the most commonly used type of behavioral biometrics?

> Which category of biometrics is more concerned with the way a human performs an action, rather than focusing on a specific physiological trait?

> Which type of scans are the least accurate form of forensic biometrics currently available in the physiological category?

> What is RISC? Why is RISC particularly beneficial for law enforcement officers?

> What are the two primary types of forensic biometrics?

> What is NPPS? What possible outcome(s) may result with the addition of NPPS to the NGI?

> Which system within the NGI has a criminal database containing 30 million front-facing mugshot photos of individuals with tenprints on file?

> What are the three most widely accepted techniques used to create a viable reconstruction and analysis of a human face?

> Indicate the order in which the bullet holes were made in the glass depicted in the accompanying figure. Explain the reason for your answer.

> What is the Eigenface technique?

> What is one significant advantage of automated facial recognition, as compared to other forms of biometrics such as iris and fingerprint systems?

> The NIR wavelength band is located within what nm range of the electromagnetic spectrum?

> What are some of the reasons why iris biometrics is replacing retina biometrics?

> What is one of the main problems with retina biometrics?

> When did the first documented attempt to identify someone using the iris occur? Who was responsible for this attempt?

> At which stage of pregnancy does the iris began to form?

> What are the two main functions of biometrics?

> What is the final step in fingerprint identification? Why is this step necessary if a computerized database of fingerprints is available to the forensic scientist?

> Briefly describe how the Automated Fingerprint Identification System (AFIS) creates a fingerprint image. What characteristics of the fingerprint does the AFIS record for comparison?

> An accident investigator arrives at the scene of a hit-and- run collision. The driver who remained at the scene reports that the windshield or a side window of the car that struck him shattered on impact. The investigator searches the accident site and c

> What aspect of a fingerprint forms the basis for primary classification under the FBI system? What is the main drawback of the FBI system?

> Describe each of the three classes of fingerprints. Which class is the most common in the population? Which is least common?

> Why is it almost impossible to obscure one’s fingerprints by surgery or mutilation?

> What is the dermal papillae and why is it important in fingerprinting?

> What aspect of a fingerprint determines its individuality?

> What major advance in fingerprint technology was pioneered by Juan Vucetich and Sir Richard Henry? What was the importance of this advance?

> What is digital imaging and how is it used in fingerprint analysis? What is the greatest limitation to digital imaging?

> When should a fingerprint be “lifted” from a crime scene? Describe how to lift and preserve a fingerprint using adhesive tape.

> What phenomenon underlies many of the new chemical techniques used to visualize latent fingerprints? Why is this phenomenon so valuable in fingerprint visualization?

> What is the most commonly used chemical method to visualize latent fingerprints on porous materials? If this method is unsuccessful, what other technique typically is used?

> Gunshot residue patterns (A) through (D) (contact, 1 inch, 6 inches, and 18 inches) from a 40-caliber pistol are shown in the figures. Match the firing distance to each pattern.

> List two types of specialized fingerprint powders and name one advantage each has over traditional fingerprint powder.

> List and describe the three types of fingerprints that may be found at a crime scene.

> Who published the first book on the science of fingerprinting? What were the book’s most important contributions to understanding fingerprints?

> Distinguish between a homicide and a suicide.

> List the five categories of the manner of death.

> Describe important factors in characterizing a gunshot wound.

> Describe the characteristics of a sharp force injury.

> Describe the characteristics of a blunt force injury

> A primary objective of the autopsy is to determine the cause of death. Define cause of death.

> Describe what’s entailed in an internal examination during an autopsy.

> How would you go about collecting impressions in each of the following situations? a. You discover a shoe print in dry dirt. b. You discover a tool mark on a windowsill. c. You discover tire marks in soft earth. d. You discover a shoe print on a loose pi

> Describe what’s entailed in an external examination during an autopsy.