lab exam - definitions Flashcards
surface tension
the tendency of liquid surfaces at rest to shrink into the minimum surface area possible
directionality
combination of the direction of travel and the angle of impact. It indicates the direction the blood was traveling when it impacted the target surface
angle of impact
the angle at which a blood drop strikes a surface
point of convergence
the point of intersection generated by lines drawn through the long axes of individual stains that indicates in two dimensions the location of the blood source
point of origin
the three-dimensional location from which blood spatter originated
force vs stain size relationship
the higher the force is, the smaller the bloodstain will be
projected bloodstain
created when an exposed blood source is subjected to an action or force, greater than the force of gravity
transfer bloodstain
result from objects coming into contact with existing bloodstains and leaving wipes, swipes, or pattern transfers behind
passive bloodstain
result from gravity acting on an injured body
scalloping
edge pattern. Can help indicate the height from which the drop fell and the directionality.
drip pattern
results from a liquid that dripped into another liquid, at least one of which was blood. Often surrounded by satellite stains
satellite stain
a smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface
spill pattern
result of a volume of blood that falls or spills on a surface
pool pattern
result of an accumulation of liquid blood falling at low velocity/from a low point on a surface
low velocity impact stain
external force of less than 5 fps creating stains generally 3 mm and larger
medium velocity impact stain
external force of 5 to 25 fps (force applied by a person using a tool) creating stains between 1 and 3 mm. Radial patterns are common and distributed like the spokes of a wheel
high velocity impact stain
external force applied to blood source is greater than 100 fps creating stains less than 1 mm (mist). Presence of back spatter that can go on the assailant and forward spatter from the exit wound
arterial gush
results from blood exiting the body under pressure from a breached artery. Creates somewhat of a stair-like pattern
Expirated stain
caused by blood from an internal injury mixing with air from the lungs being expelled through the nose, mouth, or an injury to the airways or lungs
castoff pattern
result of the centrifugal force as the weapon is swung back over the attacker’s head (tangential to arc of swing). 90° at wall and ceiling. Number of hits is always number of patterns visible + 1
swipe
pattern resulting from the transfer of blood from a blood-bearing surface onto another surface, with characteristics that indicate relative motion between the two surfaces
wipe
an altered bloodstain pattern resulting from an object moving through a pre-existing wet bloodstain
action
the functional mechanism of a breech-loading firearm that handles (loads, locks, fires, extracts, and ejects) the ammunition cartridges, or the method by which that mechanism works
ballistic coefficient
measure of a body’s ability to overcome air resistance in flight
black powder
gunpowder. Consists of a mixture of sulfur, carbon (in the form of charcoal), and potassium nitrate (saltpeter)
bolt action
a type of manual firearm action that is operated by directly manipulating the bolt (part that goes back and forth) via a bolt handle
break action
a type of manual firearm action in which the barrel or barrels are hinged much like a door and rotate perpendicularly to the bore axis to expose the breech and allow loading and unloading of cartridges
caliber
the internal diameter or bore of a gun barrel
cartridge
a tube containing an explosive substance and often a bullet
center fire
a firearm metallic cartridge whose primer is located at the center of the base of its casing
chamber
the cavity at the back end of a breech-loader’s barrel or cylinder, where the cartridge is inserted before being fired
choke
a tapered constriction of a gun barrel at the muzzle end
clip
a device that is used to store multiple rounds of ammunition together as a unit for insertion into the magazine or cylinder of a firearm
core
Conservation and Outdoor Recreation Education
extractor
in breechloading firearms, it is an action component that serves to remove spent casings of previously fired cartridges from the chamber, in order to vacate the chamber for loading a fresh round of ammunition
firing pin
the round protrusion that strikes the primer of a cartridge
forcing cone
the area in a shotgun barrel just in front of the chamber that directs the shot load into the bore
frangible
these bullets are intended to disintegrate into tiny particles upon target impact to minimize their penetration of other objects
frizzen
L-shaped piece of steel hinged at the front used in flintlock firearms. Historically called the hammer or the steel
gauge
determined by the number of lead balls of size equal to the approximate diameter of the bore that it takes to weigh one pound
grain
basic weight of the bullet
half-cock
the position of the hammer of a firearm when about half retracted and held by the sear so that it cannot be operated by a pull on the trigger
hammer
a part of the firearm that is used to strike the percussion cap/primer, or a separate firing pin, to ignite the propellant and fire the projectile
hang fire
happens when the firing pin has struck the primer and there is a delay before the gun fires
headspace
the distance measured from a closed chamber’s breech face to the chamber feature that limits the insertion depth of a cartridge placed in it
headstamp
markings on the bottom of a cartridge case
jacket
FMJ is a bullet that has a soft core, usually with lead, and is encased in a harder alloy metal such as curponickel or gliding metal
lever action
a type of firearm action which uses a lever located around the trigger guard area to load fresh cartridges into the chamber of the barrel when the lever is worked
magazine
an ammunition storage and feeding device for a repeating firearm
meplat
the technical term for the flat or open tip on the nose of a bullet
muzzle
the front end of a barrel from which the projectile will exit
ogive
the curve of a bullet’s forward section
pump action
also called slide action, it is a repeating firearm action that is operated manually by moving a sliding handguard on the gun’s forestock
revolver
a pistol with revolving chamber enabling several shots to be fired without reloading
rifling
the arrangement of spiral grooves on the inside of a rifle barrel
rimfire
relating to or denoting guns whose cartridges have the primer around the edge of the base
sabot
a device which ensures the correct positioning of a bullet or shell in the barrel of a gun, attached either to the projectile or inside the barrel and falling away as it leaves the muzzle
shank
a makeshift knife or stabbing weapon
single action
pulling the trigger does one action: it releases the hammer or the striker. If the gun’s not cocked, pulling the trigger does nothing
slug
a shotgun projectile having a round nose, a hollow base, and sides cut with a series of oblique grooves that increase the accuracy of the projectile by causing it to rotate as it passes through the smooth bore of the shotgun
wadcutter
a special-purpose flat-fronted bullet specifically designed for shooting paper targets, usually at short range and at subsonic velocities
BAC
blood alcohol concentration
MAE
when the individual was drinking just before the collecting of the breath sample, residual ethanol may remain in the oral cavity, mixed with oral fluid, which can contribute significantly to the total ethanol present in the sample and make the BAC appear much higher than it actually is
ratio of blood alcohol to alveolar air alcohol
about 2100:1, meaning that 1 ml of blood has 2100 times more ethanol than 1 ml of air from the lungs
ratio of blood alcohol to saliva alcohol
1:1
warn range
BAC between 0.05 and 0.079
field sobriety tests
groups of three tests used by police to determine if a driver is impaired. The tasks assess balance, coordination, and the ability of the driver to divide his attention to more than one task during the field sobriety test
qualitative test
identification of some or all of the constituents of the system
quantitative test
measuring the concentration (or mass) of some or all of the constituents in a system
volatility
the tendency of a substance to evaporate at normal temperatures
deep lung air
roughly the last 1/3 of an exhalation following a moderate breath in
depressant
drug that inhibits the function of the central nervous system (CNS)
air blank
the Intoxylizer 8000C collects a sample of the ambient air (which is called the air blank) to use it as a control sample
ambient fail
message that appears when the Intoxylizer detects the presence of alcohol in the air blank
purge fail
message that appears if alcohol is still detected after the instrument purged the alcohol-laden air
invalid sample
message that appears due to alcohol evaporating during the breath sampling
presumptive test
simple test for a given substance using a reagent that changes colour when mixed with the substance under investigation. It is not definitive and further confirmatory tests are always required
confirmatory test
second analytical test that can identify with certainty what the substance is (or isn’t)
GC-MS
gas chromatography mass spectrometry, used mainly for the analysis of drugs and sometimes alcohol. GC is based on differences in boiling point and provides retention time data, whereas MS provides structural information about the substance
dilutant/diluent
the diluting agent. The words are synonyms
false positive
when a positive result is obtained in the absence of the component the substance was tested for
hallucinogen
group of drugs that can produce altered states of consciousness characterized by major alterations in thought, mood, and perception, among other things (can cause hallucinations). Many cause little toxicity to organ systems (so not very fatal) and not typically considered to be habit-forming
narcotic
a drug or other substance that affects mood or behavior and is consumed for nonmedicinal purposes, especially one sold illegally
stimulant
a substance that raises levels of physiological or nervous activity in the body
opioids
class of drugs that work in the brain to produce a variety of effects, including the relief of pain
pharmacodynamics
the branch of pharmacology concerned with the effects of drugs and the mechanism of their action
pharmacokinetics
the study of the time course of drug absorption, distribution, metabolism, and excretion
loop
type of print pattern in which one or more friction ridges enter on one side of the print, curve up and around and back down, then flow out on the same side of the print from which it entered. Most common type of prints
whorl
form circular patterns, like tiny whirlpools
arch
have ridges that form a hill or look like they have a pointed tent shape. Least common type of prints
tented arch
type of print pattern similar to the plain arch but that possesses an angle, upthrust (central rise), or two of the three basic characteristics of the loop
accidental
irregular shaped. Can be a mix of two or more different patterns or have a pattern that doesn’t conform to any of the definitions
ulnar loop
have at least one ridge that starts on the little finger side, extends across the finger and curves back to the little finger side
radial loop
have at least one ridge that starts on the thumb side, extends across the finger and curves back to the thumb side
Sir William Herschel
first individual to use fingerprints on a large scale. Was a British government official living in India. He introduced fingerprint identification on a wide scale in his province in India but failed to attract interest back in England
Henry Faulds
a Scottish doctor living in Japan who was the first to help the police solve a crime based on fingerprints
Sir Edward Henry
invented a classification system that is still in use today
ridge ending
minutiae point at the ending of a friction ridge of a fingerprint
bifurcation
point where a friction ridge forks and becomes two separate ridges
island
a single small ridge inside a short ridge or ridge ending that is not connected to any other ridges
enclosure
formation where ridge bifurcates and rejoins to be one in a short distance
core
the innermost turning point where the fingerprint ridges form a loop
delta
a point in loop and whorl prints that lies within an often triangular, three-pronged, or funnel-shaped structure
ridge count
the number of lines intersected if you were to draw a line from the delta to the core plus or minus 1
minutiae
the points where the ridge lines end or fork
friction ridges
a raised portion of the epidermis on the palmar or plantar skin, consisting of one or more connected ridge units of friction ridge skin
latent prints
results from the positive reproduction of friction ridges onto a surface of some kind. They are undetectable until developed by a physical or chemical process
inked prints
the intentional recording of the friction ridge skin using black ink
10-card
a form used to record and preserve a person’s fingerprints (usually by law enforcement)
central pocket loop
a loop with a whorl at the end
double loop whorl
two loops that create an S-like pattern
Masao Soba
developed superglue fuming (cyanoacrylate)
2D footprint
footwear impression on a hard surface (doesn’t have depth)
3D footprint
footwear impression on a soft surface (has depth)
accidental characteristics
unique marks and features that develop on any item resulting from wear and tear
Bio-Foam
easily compressible impression foam that was originally engineered for orthotic and pediatric modeling
cast
made by pouring a mix of water and a powdered stone material, such as dental stone, into an impression. When it dries, it can be removed and creates a 3D model
class characteristics
those characteristics that result from the manufacturing process, such as physical size, design, and mold characteristics
elements/blocks
a single component (lug, herringbone, wave, circle, etc.) of a footwear sole distinguished by its shape that, by itself or with other design elements, comprises the tread design on that sole
full circumference tire impression
an impression of a tire that represents a full rotation of that tire under load and thus represents its entire tread surface
gait
the way a person walks
grooves
the space or channels that separate the tread ribs and elements
insole
a cushioned liner that occupies the inner surface of an item of footwear where the footrests and is placed there for comfort or protection. May be removable
last
a form made of wood, metal, or synthetic material that approximates the size and shape of a foot. The upper of the footwear is stretched over the last and held in a specific shape and size throughout the manufacturing process. The size on the manufacturer’s label is directly related to the size of the last
midsole
a component positioned between the upper and the outsole on some footwear to provide cushioning and support
negative impression
an impression that has resulted from the removal of a substance from a substrate by a footwear outsole or tire tread
oblique lighting
illumination from a light source that is at a low angle of incidence, or even parallel, to the surface of the item
offset
the distance from the wheel’s centerline to the wheel’s mounting surface. Offset is measured as positive or negative
outsole
the outermost layer of the sole of a boot or shoe, especially an athletic shoe
patent impression
an impression visible to the naked eye
positive impression
an impression that results when a shoe or tire deposits material onto a surface
pronate
walk or run with most of the weight on the inside edge of the feet
randomly acquired characteristics
a feature on a footwear outsole or tire tread resulting from random events. The position, orientation, size, and shape of these characteristics contribute to the uniqueness of a footwear outsole or tire tread. They are essential for an identification of a particular item of footwear or tire as the source of an impression
release agent
any product that prevents soil from adhering to the cast
retread
go back over (a path or one’s steps)
ribs
row of continuous rubber or disconnected tire tread blocks that run circumferentially around a tire to form the tread pattern, further distinguished as center, intermediate, or shoulder ribs
rim diameter
diameter of the rim that supports the tire bead, in inches
rolling circumference
the linear distance traveled by a tire in one revolution under load
shoulder
the portion of the tire where the tread and the sidewall meet
sidewall
the portion of the tire between the shoulder and the bead that contains the tire information
sipes
thin slits in a footwear outsole or tire tread to create better traction
supinate
walk or run with most of the weight on the outside of the feet
tire footprint/contact patch
the contact area of a tire tread against a flat surface when under load
track width
the distance between the center points of the tires from one side of the vehicle to the other
tread
the designed part of the tire that comes into contact with the road
tread block
a shape arranged circumferentially around a tire tread that together form the tread design
tread depth
a vertical measurement between the top of the tread to the bottom of the tire’s deepest groove, measured in 32nds of an inch
tread width
the width of the tire tread from one edge to the other in an impression
vulcanization
a process in which a rubber compound is heated under pressure causing a chemical change which transforms the rubber from a soft, tacky substance to tough, hard rubber
wheelbase
the distance between the front and rear axles of a vehicle. An approximation of this dimension can be obtained by measuring the distance from the leading edge of the rear tire track to the leading edge of the front tire track on the same side of the vehicle
angle of incidence
the angle an incident line or ray makes with a perpendicular to the surface at the point of incidence
angle of refraction
the angle made by a refracted ray with a perpendicular to the refracting surface
annealing
heat (metal or glass) and allow it to cool slowly, in order to remove internal stresses and toughen it
anisotropy
the property of substances to exhibit variations in physical properties along different molecular axes
Becke lines
lines that show the outline of the glass sample in the liquid due to differences in refractive indices
concentric cracks
fractures forming an approximately circular pattern around the point of impact
conchoidal fractures
it describes the way that brittle materials break or fracture when they do not follow any natural planes of separation
density
a measure of mass per volume
etching
glass etching comprises the techniques of creating art on the surface of glass by applying acidic, caustic, or abrasive substances
frosting
produced by the sandblasting or acid etching of clear sheet glass. This creates a pitted surface on one side of the glass pane and has the effect of rendering the glass translucent by scattering the light which passes through, thus blurring images while still transmitting light
hertzian cone
produced when an object passes through a solid, such as a bullet through glass. More technically, it is a cone of force that propagates through a brittle, amorphous or cryptocrystalline solid material from a point of impact
hackle
a line on the crack surface running parallel to the local direction of crack spreading
isotropy
uniform in all directions. Exhibit the same material properties in all directions
mold marks
marks on glass that are made from being blown into a mold (often seems or markings)
polish lines
lines and markings made due to polishing the glass
radial cracks
fractures extending outward from the point of impact
ream
an imperfection. Non-homogeneous layers of flat glass
refractive index
a dimensionless number that describes how fast light travels through the material
rouge pits
defects due to polishing
thermal history
the heating and cooling of glass both during and after manufacturing will affect the physical properties of the glass
Wallner lines (ridges)
rib-shaped marks with a wave-like pattern
cuticle
the outermost part of the hair shaft. It is formed from dead cells overlapping in layers, which form scales that strengthen and protect the hair shaft
cortex
located between the hair cuticle and medulla and is the thickest hair layer. it also contains most of the hair’s pigment, giving the hair its colour
medulla
the innermost layer of the hair shaft. This nearly invisible layer is the softest and most fragile
cortical fuzi
tiny air bubbles in the cortex, which appear black under the microscope. Typically, larger than pigment granules
coronal
scale pattern is found in hairs of very fine diameter and resemble a stack of paper cups
imbricate
flattened scales. Overlapping with narrow margins
spinous
petal-like scales. Triangular and protrude from hair shaft
follicle
a sac from which hair grows and into which sebaceous glands open
root
the part of the hair below the surface of the skin. It is therefore the part of the hair that includes and/or interacts with many other associated structures within the dermis and hypodermis layers of skin
anogen
the active phase of the hair growth cycle
catagen
repression of the hair follicle phase
telogen
the resting stage
follicular tag
a translucent piece of tissue surrounding the hair’s shaft near the root that contains the richest source of nuclear DNA associated with hair
polymers
a substance that has a molecular structure consisting chiefly or entirely of a large number of similar units bonded together
monomers
a molecule that can be bonded to other identical molecules to form a polymer
carbon black
a fine carbon powder used as a pigment, made by burning hydrocarbons in insufficient air. Used in ink
chromatography
technique involving the reaction of a small piece of the document containing the ink with a special solvent. The ink is then subjected to liquid chromatography that helps determine its source and components
counterfeit
made in exact imitation of something valuable or important with the intention to deceive or defraud. A fraudulent imitation of something else (forgery)
course of businees writing/non-request writing
examples of writing that are taken in the normal course of business or personal transactions
cursive
written with the characters joined
erasure
the removal of writing, recorded material, or data
ESDA
electrostatic deposition analysis: a technique used to check the sequence in which a statement written in police custody was made. The chronology of the statement is arrived at by the examination of indentations on subsequent pages
forgery
the action of forging or producing a copy of a document, signature, banknote, or work of art
freehand imitation/simulated forgery
a fraudulent signature which was executed purely by simulation rather than by tracing the outline of a genuine signature
graphite
a grey crystalline allotropic form of carbon which occurs as a mineral in some rocks
graphology
study of the inference of character from a person’s handwriting
hand printing
printed, or put on a surface, by hand rather than by machine
holographic document
a document written entirely in the handwriting of the person whose signature it bears
indentations
the impression from the writing instrument captured on sheets of paper below the one that contains the original writing
ink formula
colorants, carriers, and additives
iron gallontannate
when tannic acid (which is plentiful in red oak), water (which is plentiful in freshly sawn oak), and iron (from a saw, forklift forks, metal bands, etc.) are mixed, the result is iron tannate, a blue-black-coloured chemical
kiting
the fraudulent writing or use of a check, bill, or receipt
kaolin
a fine soft white clay, resulting from the natural decomposition of other clays or feldspar. It is used for making porcelain and china, as a filler in paper and textiles, and in medicinal absorbents
line quality
used to describe the character and aspects of the linear mark-making in a work of art. it is not a scale of good to bad or less to more skilled; instead, it calls attention to the “hand feel” of the marks. It references the variation in width, smoothness, movement, briskness, depth, etc.
model signature
signature that was used as a “model” for the forgery
provenience
a record of ownership of a work of art or antique, used as a guide to authenticity or quality
request writings/exemplars
legally admissible authentic samples of handwriting used for comparison with the questioned writing
water mark
translucent pattern, visible when the paper is held to the light
