Forensics Exam 2 Chapters 6 - 10

What physical change occurs when a substance undergoes the following changes of state: (a) from liquid to solid, and (b) from liquid to gas?

(a) freezing (b) evaporation

List two unique characteristics of the stereoscopic microscope.

1. Create right side-up image 2. Distinctive 3-dimensional image

Describe how to lift and preserve a fingerprint using adhesive tape.

1. Dust the print with fingerprint powder. 2. Cover the print with adhesive tape 3. Pull the tape off carefully and the print should be on the tape. 4. Place the tape on a card and take it back to the lab.

Biometric Identification

A biometric system that can distinguish between subjects by analyzing a biometric trait of one person and compare it against an existing database of enrolled traits

Facial Recognition

A biometric technology that looks for unique measurements in an individual's face. Analyze cheekbones, mouth edges, chin, ridges between the eyebrows, the contour of the jawline, distance between the eyes, widow's peak, and many other data points.

Becke Line

A bright halo that is observed near the border of a particle immersed in a liquid of a different refractive index.

Sublimation

A change directly from the solid to the gaseous state without becoming liquid.

Periodic Table

A chart of elements arranged in a systematic fashion; vertical rows are called groups or families and horizontal rows are called series; elements in a given row have similar properties.

DFO

A chemical fingerprint developer (1,8-diazafluoren-9-one). Treat ninhydrin prints with this salt. Converts Ruhemann's purple to a fluorescent one that can be seen with a light source.

Ninhydrin

A chemical reagent used to develop latent fingerprints on porous materials by reacting with amino acids in perspiration.

Greiss Test

A chemical test used to develop patterns of gunpowder residues around bullet holes.

Luminol

A chemical that emits a blue glow when it comes in contact with blood

Small Particle Reagent (SPR)

A chemical used to process wet or greasy items for latent fingerprints. Useful for nonporous surfaces. Spray or immerse print.

Physical State

A condition or stage in the form of matter; a solid, liquid, or gas

Radial Fractures

A crack in a glass that extends outward like the spoke of a wheel from the point at which the glass was struck.

Concentric Fractures

A crack in a glass that forms of a rough circle around the point of impact.

Birefringence

A difference in the two indices of refraction exhibited by most crystalline materials.

Firearms Identification

A discipline mainly concerned with determining whether a bullet or cartridge was fired by a particular weapon; it is not to be confused with ballistics, which is the study of a projectile in motion.

Plastic Print

A fingerprint impressed in a soft surface. Such as putty, wax, soap, or dust.

Visible Print

A fingerprint made when the finger deposits a visible material such as ink, dirt, or blood onto a surface.

What are some steps used to analyze bite marks and impressions of teeth? Describe how they are helpful.

A forensic dentist is called in as the expert. Bite mark is identified as human. The area is swabbed for DNA. Measurements are taken of the bite mark. Often the area is excised or casted to keep as evidence. Molds are made of suspects teeth to use as a comparison.

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

A forensic odontologist might be asked to analyze bite marks on a person or object found at a crime scene. If a sufficient number of points of similarity exist between the test and suspect marks, the forensic odontologist may conclude that the marks were made by one particular individual

What is the primary disadvantage with Principal Component Analysis?

A full frontal face image is needed to be a viable sample

Element

A fundamental particle of matter; an element cannot be broken down into simpler substances by chemical means.

Bullet Wipe

A gray or black ring around an entrance bullet hole

Xray

A high-energy, short-wavelength form of electromagnetic radiation.

What are dermal papillae and how are they important in fingerprinting?

A layer of cells separating epidermis and dermis that creates the pattern or ridges on the surface of the skin.

Compound Microscope

A light microscope that uses more than one lens to magnify an object. The passage of light through two lenses forms the virtual image of the object seen by the eye.

Comparison Microscope

A microscope that has two compound light microscopes with an optical bridge, so that two samples can be viewed in a single eyepiece. It is used to match trace evidence such as fibers and bullet casings.

Polarizing Microscope

A microscope that illuminates the specimen with polarized light.

Density

A physical property of matter that is equivalent to the mass per unit volume of a substance.

Digital Imaging

A process through which a picture is converted into a series of square electronic dots known as pixels; the picture is manipulated by computer software that changes the numerical value of each pixel.

Weight

A property of matter that depends on both the mass of a substance and the effects of gravity on that mass.

Intensive Property

A property that is not dependent on the size of an object.

Define intensive property and name two intensive properties of matter.

A property that is not dependent on the size of an object. Density and refractive index.

Compound

A pure substance composed of two or more elements.

Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

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

A scanning electron microscope uses a stream of electrons to create an image of the specimen being studies; all other microscopes uses light coming off the specimen to create an image

Physical Developer

A silver nitrate-based reagent formulated to develop latent fingerprints on porous surfaces.

Photon

A small packet of electromagnetic radiation energy; each photon contains a unit of energy equal to the product of Planck's constant and the frequency of radiation: E = hf

Crystalline Solid

A solid in which the constituent atoms have a regular arrangement.

Amorphous Solid

A solid in which the constituent atoms or molecules are arranged in random or disordered positions; there is no regular order in amorphous solids.

Pixel

A square electronic dot that is used to compose a digital image.

To explain the events that occur after radiation is absorbed by a substance, light must be characterized as:

A stream of discrete particles.

Anthropometry

A system of identification of individuals by measurement of parts of the body, developed by Alphonse Bertillon.

Iodine Fuming

A technique for visualizing latent fingerprints by exposing them to iodine vapors.

Superglue Fuming

A technique for visualizing latent fingerprints on nonporous surfaces by exposing them to cyanoacrylate vapors; named for the commercial product superglue.

SEM Stub

Adhesive stub used to sample a suspect's shooter's hands.

Automated Fingerprint Identification System (AFIS)

Aids in classifying and retrieving fingerprints. Converts the images of a fingerprint into digital minutiae that contain data showing ridges at their points of termination (ridge endings) and their branching into two ridges (bifurcations). Integrated into the NGI system in 2014.

Matter

All things of substance; matter is composed of atoms or molecules.

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

All-around better technology, which if functional for both law enforcement and business security. Retina scanners are largely outdated and considered too intrusive to be practical in real-world applications. Retina technology is hard to implement and poses problems in the field. System itself requires lots of training to use for retina scans. Usability: Iris scan can be acquired with a photograph, with the end user standing a reasonable distance from a camera and a simple picture being taken. Retina scans, require the user to have their eyeball within a fraction of an inch of a high-power camera lens. The process may take an extended period of time, and can be uncomfortable.

Laser

An acronym for light amplification by stimulated emission of radiation; light that has all its waves pulsating in unison.

Two-dimensional imprints found at a crime scene can be lifted using:

An electrostatic lifting device

Livescan

An inkless device that captures the digital images of fingerprints and palm prints and electronically transmits the images to an AFIS.

Microspectrophotometer

An instrument that links a microscope to a spectrophotometer. Useful for trace evidence.

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?

An investigator would not pick up a weapon by its barrel with a pencil or stick in order to protect fingerprints because this may disturb powder deposits, rust, or dirt lodged in the barrel, and consequently may alter the striation markings on test-fired bullets. If the recovery of latent fingerprints is a primary concern, it is best to hold the weapon by the edge of the trigger guard or by the checkered portion of the grip.

Which step of the ACE-V process requires the examiner to identify any distortions associated with the friction ridges?

Analysis

ACE-V

Analysis - Identify any distortions associated with friction ridges, as well as any external factors or processing techniques, that may impinge on the print's appearance. Comparison - Compare the questioned print to the known print at three levels. Side by Side comparison. Evaluation - Requires one of three decisions to be arrived at. Identification (the latent print and exemplar came from the same source). Exclusion (the latent print and exemplar did not come from the same source). Inconclusive (one cannot determine that the latent print and exemplar came from the same source). Verification - Requires an independent examination of the questioned and known prints by a second examiner.

Why does analysis of primer residue from a suspect's hands produce a low rate of positive results?

Analysis of primer residue from a suspect' shands produces a low rate of positive results because primer residues remain on the hands only for a short time and are easily removed by rubbing or washing. This technique cannot be used to detect firings with most .22-caliber rim-fire ammunition because the primer for this ammunition often does not contain characteristic elements associated with primer residues.

Tool Mark

Any impression, cut, gouge, or abrasion made when contact occurs between a tool and another object

Which statement is true of a partial fingerprint?

Any print can identify a criminal if it shows an adequate number of ridge characteristics.

Livescan images of fingerprints:

Are captured when the subject's fingers and palms are placed onto a glass platen. Have eliminated the need for inked prints on paper cards. Are sent to the AFIS database electronically.

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

Attempt is made to remove any gunshot particles that remain on a shooter's hand with a piece of adhesive tape. Examine under SEM for presence of particles that may have originated from the bullet primer. Characterized by their shape, size, and elemental composition. Through the use of this technique, the elements lead, antimony, and barium are frequently found in most primers and can be rapidly detected and identified. Examiners measure the amount of barium and antimony. X-ray analyzer detects and displays x-ray emissions from the elements lead, antimony, and barium.

Why is the metric system of measurement easier to use than the "English System"? Which system is used in the United States?

Based on the power of 10. English System

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

Because as magnification increases, field of view decreases.

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

Before any impression is moved or otherwise handled, it must be photographed to show all the observable details of the impression. Photography is considered merely a backup procedure in case the impression is damaged before reaching the crime laboratory. It is preferable for the examiner to receive the actual impression for comparison to the suspect object that made the impression.

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

Behavioral Biometrics

What are the two main functions of biometrics?

Biometric Matching or Verification and Biometric Identification

What function of biometrics would law enforcement be implementing if they wanted to look for a person of interest accused of sexual assault in a large crowd at a sports stadium?

Biometric matching or verification

Which of the following pathways would represent an accurate portrayal depicting the collections steps in gathering biometric data?

Biometric sensor Pre-processing Feature Extractor Template generator

Biometric Matching or Verification

Biometric systems capable of identifying someone out of a crowd by scanning select biometric characteristics into a database. Law enforcement entities implement this form of biometrics to find wanted fugitives and individuals suspected of terrorism.

What reference points are most often chosen when constructing a temperature scale?

Boiling Point and Freezing Point

How would a forensic odontologist be able to determine that teeth were from a young child?

By looking at the number and size of the teeth. Also if they are baby or adult teeth.

How does magnifying glass enlarge objects viewed through it?

By refracting light

________ is the visual effect caused by an object's absorption of certain portions of the visible light spectrum and transmission or reflection of others.

Color

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

Color is the quality of an object with respect to light reflected by the object. The wavelength of the reflected light.

Visible Light

Colored light ranging from red to violet in the electromagnetic spectrum.

AFIS is a(n):

Computerized system for storing and retrieving fingerprint records

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

Consist of two compound microscopes connected by a bridge when you look down you see two things side by side. It's used to compare two specimens to see if they come from the same source.

National Palm Print System (NPPS)

Contains a database of millions of palm prints to be used in criminal investigations and processes.

Retina

Contains sensory receptors that process visual information and sends it to the brain. Back of the eye where neural information is processed.

Briefly describe how the Automated Fingerprint Identification System (AFIS) creates a fingerprint image.

Convert the image of a fingerprint into digital minutiae that contain data showing ridges at their points of termination (ridge endings) and the branching of ridges into two ridges (bifurcations). The relative position and orientation of the minutiae are also determined, allowing the computer to store each fingerprint in the form of a digitally recorded geometric pattern.

Metric Conversion

Converting units from the metric system into the English system, or vice versa. 1 in = 2.54 cm 1 meter = 39.37 in 1 pound = 453.6 grams 1 liter = 1.06 quarts 1 kilogram = 2.2 pounds

Which of the following is NOT a ridge characteristic of a fingerprint?

Core

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?

Crystalline solids are in an ordered arrangement Amorphous solids are in a random arrangement Amorphous- has only one refractive index Crystalline- has two refractive indexs

Crystalline solids, with the exception of ________ crystals, exhibit ________, or the property of refracting a beam of light into two different ray components.

Cubic, double refraction

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?

Current efforts to identify a shooter center on the detection of primer residues deposited on the hand of a shooter at the time of firing. Residues are most likely to be deposited on the thumb web and the back of the firing hand of a shooter, because these areas are in closest proximity to gases escaping along the side or back of the gun during discharge.

Flotation is a method used by scientists to determine the ________ of a particle of glass

Density

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

Density = mass/volume As the temperature rises, the density of a gas or a solid decreases.

Integrated Ballistic Identification System (IBIS)

Developed for the Bureau of Alcohol, Tobacco, Firearms, and Explosives. Processed digital microscopic images of identifying features found on expended bullets and cartridge casings.

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

Developed methods to classify, store, and file prints. Primary Classification Method. The creation of classification systems capable of filing many prints in a logical sequence. The importance of this advance is that it allowed law enforcement officials to compare prints found at crime scenes to known criminals. Provides examiners with a number of candidates.

What were "Finger Prints" most important contributions to understanding fingerprints?

Discussed the anatomy of fingerprints and suggested methods for recording them. Proposed assigning fingerprints to three pattern types. Most importantly, the book demonstrated that no two prints were identical and that an individual's prints remain unchanged from year to year.

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?

Distance determination for a shotgun blast is made by measuring the spread of the discharged shot--the wider the spread, the farther the shooter was from the target. Other factors include the barrel length, the size and quantity of the pellets fired, the quantity of powder charge used to propel the pellets, and the choke of the gun (the degree of constriction placed at the muzzle end of the barrel)

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

Distance determination is the process of determining the distance between the firearm and a target, usually based on the distribution of powder patterns or the spread of a shot pattern. If a suspect pleads self-defense as the motive for a shooting, determining how far apart the suspect and victim were at the time of shooting can establish the facts of the incident. Distance determination can also determine whether a shooting was suicide, which usually involves a very close-range gunshot wound. The absence of characteristics consistent with a close-range shot is a strong indication that the would was not self-inflicted and signals the possibility of foul play.

Whorl

Divided into four distinct groups; Plain whorl, central pocket loop, double loop, and accidental.

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

Does not require subjects to participate.

Infrared

Electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves

Elemental Profile

Elemental composition of glass.

The FBI has an internal unit called FACE. What does FACE stand for?

Facial Analysis, Comparison, and Evaluation

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

Facial Recognition: Can be easily tricked or spoofed.

List the two most commonly used temperature scales and their respective reference points.

Fahrenheit - Boiling = 212 degrees, Freezing = 32 degrees Celsius - Boiling = 100 degrees, Freezing = 0 degrees

Describe the process of flotation and explain what it is used for.

Flotation is when a reference glass particle is immersed in a liquid. The liquid is adjusted until the particle floats. Glass chips of approximately the same size and shape are then added to the liquid for comparison. The densities are then compared. It is used for comparing the densities of glass.

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

Fluorescent - Stops the color of the surface obscuring the print. Magnetic - Useful for leather and rough plastics. Less chance the print will be destroyed as the brush doesn't actually touch the print.

Who published the first book on the science of fingerprinting?

Francis Galton, "Finger Prints"

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

Gait refers to the cycle of walking, which is composed of several stages and is unique for everyone. Every person has a different posture, step length, speed, and foot positioning in regards to the way they walk from one place to another.

Tempered Glass

Glass that is strengthened by introducing stress through rapid heating and cooling of the glass surfaces.

List the three characteristics of a gun barrel

Grooves Lands Caliber

GSR

Gun Shot Residue

Will West was the man who:

Had a virtual "double" with a similar name

What is the Becke line and how is it used to determine the refractive index of a glass sample?

Halo observed near the border of a particle immersed in a liquid of different refractive index. Disappears when medium and fragment have similar refractive indexes.

What is the most commonly used type of behavioral biometrics?

Handwriting

Currently, which of the following, in conjunction with chemically induced fluorescence, is most often used to visualize latent prints?

High-intensity light sources

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

IPS (Interstate Photo System)

Which of the following results is not possible from a laboratory examination of firearm evidence?

Identifying a bullet as having been combined with a particular shell prior to being discharged

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

If the weapon is fired less than 1 inch from the target, a heavy concentration of smokelike vaporous lead usually surrounds the bullet entrance hole. Often, loose fibers surrounding a contact hole show scorch marks from the flame discharge of the weapon, and some synthetic fibers show signs of being melted as a result of the heat from the discharge. Furthermore, the blowback of muzzle gases may produce a stellate (star-shape) tear pattern around the hole

Reflected or Vertical Illumination

Illumination of a specimen from above; in microscopy it is used to examine opaque specimens.

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?

Illumination of a specimen from above; in microscopy it is used to examine opaque specimens. Transmitted light can't see through opaque specimens.

A wear pattern, cut, gouge, or other damage pattern can impart ________ characteristics to a shoe.

Individual

The presence of gunpowder residues on a garment whose color conceals the existence of the residue is best revealed by:

Infrared Photography

IPS System

Interstate Photo System Database containing 30 million front-facing mugshots photos of individuals with tenprints on file. Criminal Identities and Civil Identities.

IrisCodes

IrisCode is a process to analyze and store information on a human iris. This method uses the extracted data from a human iris and processes it through a quantization stage that produces a binary iris code for later comparison.

When a bullet penetrates a panel of glass, it leaves a crater-shaped hole that:

Is wider on the exit side

How did the comparison microscope makes possible modern firearms examination?

It gives the examiner a side by side magnified view of bullets. Bullets that are fired through the same rifle barrel display compatible rifling markings

Which of the following is one of the key advantages to EBGM?

Its extreme precision and accuracy

Arch

Least common of the three general patterns. No deltas, type lines, or cores. Plain Arches: Formed by ridges entering from one side of the print and exiting on the opposite side. Wavelike pattern Tented Arches: Similar to the plain arch. Sharp upthrust or spike. Less than 90 degrees.

Shoe Impressions

Left by shoe print.

List the basic units of length, mass, and volume in the metric system.

Length: Meter Mass: Gram Volume: Liter

Eyepiece or Ocular Lens

Lens closest to the eye. Monocular = one, binocular = 2

A piece of glass is immersed in a liquid. It proceeds to float on the liquid's surface. This shows that the density of the glass is ________ the density of the liquid.

Less than

The likelihood of detecting GSR on swabs taken from living subjects more than six hours after a firing has occurred is ________ the likelihood of detecting GSR within two hours of a firing.

Less than

ACE-V Comparison Levels

Level 1: Encompasses the general ridge flow and pattern configuration. Level 2: Includes locating and comparing ridge characteristics or minutiae. Level 3: Includes the examination and location of ridge pores, breaks, creases, scars, and other permanent minutiae.

Polarized Light

Light confined to a single plane of vibration.

Refraction

Light is refracted when it travels obliquely from one medium to another. The bending of light waves because of a change in velocity

Transmitted Illumination

Light that passes up from the condenser and through the specimen.

Serial Number

Link a firearm back to the owner. Found on all firearms.

Ridge Comparison

Looking at two fingerprints and their ridges to see if they're a match. Numbers that range from 8 - 16 have been suggested to meet the criteria of individuality.

Describe each of the three classes of fingerprints.

Loops - Comes in from one side and exits the same side. Ulnar -> pinky, radial -> thumb. One delta, core, two diverging type lines. Whorls - At least two deltas, have type lines. Plain, central pocket loop, double loop, and accidental. Arches - No type lines, deltas, or cores. Plain and tented arches.

Dusting to visualize a latent print on finished leather and rough plastic is best done with a:

Magna (magnetic) brush

Which of the following procedures is not to be followed in collecting and packaging firearms evidence at the crime scene?

Marking an empty cartridge case on its base for identification

Friction Ridges

Markings on the fingertips that leave distinctive oily fingerprints on surfaces we touch

Define weight and mass and explain the difference between the two concepts.

Mass differs from weight because it refers to the amount of matter an object contains and is independent of its location on earth or any other place in the universe. The weight of a body is directly related to its mass.

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

Mass made and could be too fragmented

What is NPPS? What possible outcome may result with the addition of NPPS to the NGI?

National Palm Print System. The NPPS will see great improvements in the search of latent fingerprint files from unsolved cold cases. Will be able to generate new leads for crimes that may have occurred decades ago and gone unsolved. Powerful investigative tool and may provide closure for families of murder victims.

Which of the following features would not serve as a variable for analysis in biometric facial recognition?

Neck

A technique applicable for determining whether or not an individual has recently fired a weapon is:

Neutron activation analysis The scanning electron microscope Atomic absorption analysis

NGI System

Next Generation Identification Provides a broader selection of resources and information for law enforcement agencies across the country. New Tenprint system has been implemented. The FBI has also developed a new latent print search algorithm. Rap Back Service: sends notifications to agencies throughout the US pertaining to criminal activity of individuals that have already been processed through the system at one point. Facial recognition is now being implemented for use in criminal investigations. Images taken of suspects are sent to the FBI and the Bureau compares these images to a large database in the NGI. Scars, marks, and tattoos are also being added to the NGI System.

Protein residues are best developed into fingerprint impressions with:

Ninhydrin

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

Ninhydrin - a chemical reagent used to develop latent fingerprints on porous materials by reacting with amino acids in perspiration - is the chemical method of choice due to its extreme sensitivity and ease of application. When this fails - physical developer - a silver nitrate-based reagent formulated to develop latent fingerprints on porous surfaces.

Loop

One or more ridge entering from one side of the print, recurving, and exiting from the same side. Ulnar and Radial Loops. The pattern area of the loop is surrounded by two diverging ridges called type lines. All loops must have on delta. The core is the center of the loop.

Ulnar Loop

Opens towards the pinky.

Radial Loop

Opens towards the thumb

Which facial recognition technique uses thousands of stored images of faces and places them over the face in question?

PCA

Stress marks on the edge of a radial crack near the point of impact are:

Parallel to the side on which the force was applied

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

Patent (visible) - Visible to the naked eye. Deposits a visible material such as ink, dirt, or blood onto a surface. Plastic - Impressed into a soft surface. Latent - Requires additional processing to become visible. Impressions caused by the transfer of body perspiration or oils present on finger ridges.

What are the two primary types of forensic biometrics?

Physiological and Behavioral Biometrics

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

Power of the ocular lens X power of the objective lens.

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

Presence/absence of whorls. Main drawback - local systems often are not linked to the state's AFIS system because of difference in software configurations.

The friction skin ridges

Provide a firmer grip, resist slippage

What is the main advantage of the microspectrophotometer?

Provides added info to characterize trace qualities.

Primary Classification (Henry Method)

Provides an examiner with a number of candidates, not used for identification. Converted ridge patterns on all ten fingers into a series of letters and numbers arranged in the form of a fraction.

What is the 3R rule and how is it applied to the analysis of glass fractures?

RADIAL cracks form a RIGHT angle of the REVERSE side of the force. This rule enables an examiner to determine readily the side on which a window or pane of glass was broken.

Which is a true statement about the fracturing of glass?

Radial cracks appear first, starting on the side opposite the destructive force.

The photons of which source have the LEAST amount of energy?

Radio Waves

A hot-stage microscope or the GRIM 3 is used to determine the ________ of glass fragments

Refractive Index

If glass cannot be physically pieced together then the control and question glass are best compared as to their:

Refractive Index and Density

The two most important physical properties of glass for forensic comparisons are:

Refractive Index and Density

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

Repository of Individuals of Special Concern. Allows for officers to fingerprint individuals they come in contract with and quickly detect whether or not they are a threat. May protect officers from potential danger, as they will now have a better idea of whom they are dealing with.

Latent Print

Requires additional processing to become visible. Invisible prints are impressions caused by the transfer of body perspiration or oils present on finger ridges to the surface of an object.

Primer Residue

Residue deposited on the hands and clothes of someone who discharges a firearm

Feature Extractor

Responsible for finding patterns in the traits extracted by the sensor by using mathematical equations. Retina feature extraction - distance between muscle fibers in the eye. Fingerprints extraction - identify the type of pattern (loops, whorls, and arches)

Template Generation

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.

Minutiae

Ridge characteristics used to classify and match prints.

What characteristics of the fingerprint does the AFIS record for comparison?

Ridge endings and bifurcations.

Ridge Characteristics (Minutiae)

Ridge endings, bifurcations, enclosures, and other ridge details, which must match in two fingerprints in order for their common origin to be established

The automated shoe print identification system is known as:

SICAR

What is the main ingredient in ordinary glass?

Sand

The pores of the sweat glands are located in the:

Skin Ridges

If you have an object that is wet, what methods could you use to develop the print? Why does this work?

Small Particle Reagent (SPR). A physical development technique in which small black particles adhere to the fatty substances left in print residue and is useful on many different surfaces

Atom

Smallest particle of an element

Define element and compound and name the smallest unit of each.

Smallest unit of an element is an atom. Smallest unit of a compound is a molecule.

Name the three forms, or states, of matter and explain how the shape and volume of matter are expressed in each state.

Solid - Rigid, definite shape and volume Liquid - Occupies a specific volume, takes the shape of the container. Gas - Neither a definite shape or volume

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

Stereoscope microscope. A wide field of view and the great depth of focus and large working distance makes it ideal to look at big, bulky items. Also good for detecting debris on clothing and debris.

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

Sublimation is a physical change from the solid state directly into the gaseous state. It causes the forces between molecules to decrease.

Drugfire

System emphasized the examination of unique markings on the cartridge casings expended by the weapon.

Stellate Star

Tear pattern around the bullet hole entrance surrounded by a rim of a smokeless deposit of vaporous lead. Created by a gunshot where the muzzle is either in contract with or less than 1 inch from the target.

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

Template Generation

What is the first process that each biometric system must perform?

The Enrollment Process

What biometric system process or module performs the "heavy lifting" for the system?

The Extraction Process

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

The Greiss test is a chemical test used to develop patterns of gunpowder residues around bullet holes. The test results can reveal whether powder residues from a gunshot are present and can also help determine the distance from the shooter to the target.

Pupil

The adjustable opening in the center of the eye through which light enters

Field of View

The area of the specimen that can be seen after it is magnified.

Chemical Property

The behavior of a substance when it reacts or combines with another substance.

Physical Property

The behavior of a substance without alteration of the substance's composition through a chemical reaction.

Which of the following factors is least likely to be considered by the examining tool mark technician?

The brand name of the tool

Change of State

The change of a substance from one physical state to another

The refractive index of a substance varies with:

The color of the light passing through it The wavelength of the light passing through it Its temperature

Grooves

The cut or low-lying portions between the lands in a rifled bore.

Caliber

The diameter of the bore of a rifled firearm; the caliber is usually expressed in hundredths of an inch or millimeters - for example, .22 caliber and 9mm

Wavelength

The distance between crests of adjacent waves.

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?

The distribution of gunpowder particles and other discharge residues around the bullet hole permits an assessment of the distance from which a handgun or rifle was fired. To determine the precise distance from which a gun has been fired requires a comparison of the powder-residue pattern on the victim's clothing or skin against patterns made from test-firing the suspect weapon. By comparing residue patterns from test firings to those found at the crime scene, the examiner may find enough similarity in shape and density on which to base an opinion as to the distance from which the shot was fired.

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

The edges of any tool display a series of microscopic irregularities having the appearance of ridges and valleys. These marks are created during the machining processes used to cut and finish the tool. Another type of mark caused by nicks and breaks in the tool that occur during normal use.

Electromagnetic Spectrum

The entire range of radiation energy from the most energetic cosmic rays to the least energetic radio waves.

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

The examiner must test-fire bullets through the suspect barrel because there is no other practical way to directly compare the markings on the fired bullet and those found within the barrel.

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

The examiner places both bullets under a comparison microscope, pointing in the same direction, and then rotates one bullet until a well-defined land or groove comes into view. When the examiner locates striation markings on this bullet, the other bullet is rotated until a matching region is found. When a matching area is located, the two bullets are simultaneously rotated to locate additional matching areas around the periphery of the bullets. The examiner uses the striation markings to identify bullets because no two rifled barrels have identical striation markings.

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

The firing pin, the breechface, the extractor, the ejector, the magazine, the clip, and the fire chamber walls may all leave distinctive markings on a shell casing.

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

The first model describes light as a continuous wave. The second depicts it as a stream of discrete energy particles. Together, these two very different descriptions explain all of the observed properties of light, but by itself, no one model can explain all the facets of the behavior light.

Scanning Electron Microscope (SEM)

The image is formed by aiming a beam of electrons onto the specimen and studying electron emissions on a closed TV circuit.

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

The infrared microspectrophotometer identifies a specimen by obtaining its IR spectrum, which is unique for every chemical substance. The technique is used to analyze paint, fibers, and ink evidence

Bore

The interior of a firearm barrel.

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?

The investigator should record the weapon's hammer and safety position as well as the location of all fired and unfired ammunition in the weapon. The cylinders and cartridges should be numbered because this information may be useful to determine the sequence of events, particularly in cases which several shots were fired.

Condenser

The lens system under the microscope stage that focuses light onto the specimen.

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

The light passes through two lenses forming a virtual image. It magnifies the scope by 10x.

Barrel

The long, metal tube that guides a projectile out of a firearm

Extractor

The mechanism in a firearm by which a cartridge of a fired case is withdrawn from the chamber.

Ejector

The mechanism in a firearm that throws the cartridge or fired case from the firearm.

Frequency

The number of waves that pass a given point per second.

Objective Lens

The part of a compound light microscope that is located directly above the specimen and that magnifies the image of the specimen

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

The phenomenon of fluorescence serves as the underlying principle of many of the new chemical techniques used to visualize latent fingerprints. Substances that emit light or fluoresce are more readily seen either with the naked eye or through photography as compared to non-light-emitting materials. Thus, techniques based on fluorescence permit better visualization of all prints and allow the visualization of faint prints that other methods may fail to visualize.

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

The presence of grit and rust can alter the markings on bullets fired through the same barrel. Striation markings on a barrel are not permanent structures; they are subject to continuing change and alteration through wear as succeeding bullets traverse the length of the barrel.

Enrollment Process

The process of capturing a person's biometric data and storing them in a database for later use. It works by collecting data through a sensor and sending it to a data acquisition module.

Distance Determination

The process of determining the distance between the firearm and a target, usually based on the distribution of powder patterns or the spread of a shot pattern.

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

The process through which a picture is converted into a series of square electronic dots, used to compare fingerprints and to enhance poor fingerprint images The main limitation of digital imaging is that it is only as useful as the images it has to work with. If the images are poor or incomplete, enhancement procedures will not work.

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?

The protection of class and individual markings on bullets and cartridge cases must be the primary concern of the field investigator who is handling such evidence. If the bullet's surface is accidentally scratched when removing it from a wall or other object, valuable striation markings could be obliterated that can help link the bullet to a suspect weapon.

Lands

The raised portion between the grooves in a rifled bore.

Refractive Index

The ratio of the speed of light in a vacuum to its speed in a given substance.

Breechface

The rear part of a firearm barrel.

The effect of gravity on the weight of an object is ________ the effect of gravity on the mass of the same object.

The same as

Dispersion

The separation of light into its component wavelengths.

Tempered glass is used in:

The side and rear windows of autos manufactured in the United States.

Rifling

The spiral grooves formed in the bore of a firearm barrel that impart spin to the projectile when it is fired.

Celcius Scale

The temperature scale using the melting point of ice as 0 degrees and the boiling point of water as 100 degrees, with 100 equal divisions of degrees between.

Fahrenheit Scale

The temperature scale using the melting point of ice as 32 degrees and the boiling point of water as 212 degrees, with 180 equal divisions or degrees between.

Depth of Focus

The thickness of a specimen that is entirely in focus under a microscope.

Forensic Palynology

The use of pollen and spore evidence to help solve criminal cases

How can an investigator determine the order in which several successive penetrations of a glass occurred?

They can tell by the fracture lines and where they terminate. cracks always end at an existing fracture line

Physiological Biometrics

This form of biometrics focuses on identifying humans through their unique physiological traits. Physiological biometrics includes fingerprints, hand, iris, retina, and facial scans.

Behavioral Biometrics

This form of biometrics focuses on identifying humans through unique behavioral or mental patterns they exhibit. Behavioral biometrics includes handwriting, voice, keystroke, and gait recognition.

Extraction Process

This module is responsible for finding patterns in the traits extracted by the biometric sensor by using mathematical equations. Every system uses different equations and algorithms to judge unique characteristics.

Electrostatic Lifting

This uses a sheet of Mylar film to lift markings or fingerprints

Fluoresce

To emit visible light when exposed to light of a shorter wavelength.

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

To restore an obliterated serial number, the criminalist applies a suitable etching agent to the area that has been defaced. The metal in this area dissolves at a faster rate than the unaltered metal surrounding it, thus permitting the etched pattern to appear in the form of the original numbers.

Applicants that are being entered into an iris-based biometric system need how many photographs taken of their eye?

Two

Laminated Glass

Two sheets of ordinary glass bonded together with a layer of plastic.

What aspect of a fingerprint determines its individuality?

Type and position of ridge characteristics (minutiae).

Stereoscopic Microscope

Type of microscope that consists of two side-by-side, relatively low powered compound microscopes in a common housing. Creates a 3D image.

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?

Verification: examiner's conclusion is confirmed by a second examiner. Fingerprint expert makes the final verification of the prints identity. For human verification on the off-chance AFIS made a mistake.

What is one of the main problems with retina biometrics?

Viable images can be affected by disease.

Patent Print

Visible print, doesn't need to be processed.

Which of the following would not be considered a physiological biometric?

Voice

Which is NOT a class characteristics of a suspect's sneaker?

Wear marks

What happens to a light beam that passes through a polarizing crystal? What happens when plane-polarized light passes through a second polarizing crystal set perpendicular to the first crystal?

When a beam of light passes through a polarizing crystal, it emerges vibrating in only one plane. When a plane-polarized light passes through a second polarizing crystal set perpendicular to the first, no light penetrates and the result is total darkness or extinction.

Fingerprint Powders

When applied to a non-absorbent surface with a brush, these adhere to oils or sweat left in latent prints.

When should fingerprints be "lifted" from a crime scene?

When it's on a large immovable object.

Casting

When removal of the tool is impractical, the only recourse is to photograph the marked area to scale and make a cast of the mark. Liquid silicone casting material has been found to be the most satisfactory for reproducing most of the fine details of the mark.

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?

When removal of the tool mark is impractical, the area is photographed and marked to scale, and a silicone cast of the mark is made. The disadvantage of this technique is that even under the best conditions, the clarity of many of the tool mark's minute details will be lost or obscured in a photograph or cast.

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

When the electron beam of the scanning electron microscope strikes a specimen, it creates X-rays that can be sorted by an X-ray analyzer. Because each element emits X-rays of characteristics energy values, the analyzer can identify the elements present in the specimen based on the energy values of the X-rays emitted by the specimen.

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

You would have to penetrate 1 to 2 millimeters beneath the skin's surface. The presence of permanent scars merely provides new characteristics for identification.

Superglue fuming is NOT suitable for use on:

cardboard

NIBIN is/are

database for firearm evidence

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

different objects absorb certain portions of visible light and reflect others, and it bends light it bends in different angles to produce other colors

The gauge of a shotgun is __________ to the diameter of its barrel

directly related

Fingerprints are formed

during fetal development

The barrel of a shotgun

is smooth without the grooves and lands found in rifles

States of Matter

solid, liquid, gas