Ch.4 Crime Scene Reconstruction- Blood Stain Pattern Analysis
The ___ method of bloodstain documentation involves setting up a border of rulers around the pattern and then placing a small ruler next to each stain to show relative position and size in photographs
Perimeter ruler method
The approximate drying time of a(n) ___ of blood determined by experimentation is related to the environmental condition of the scene and may suggest how much time has elapsed since its deposition
Pool
Skeletonization
The process by which the edges of a stain will dry to the surface in a specific period of time (dependent upon environmental and surface conditions) and will remain apparent even after the rest of the bloodstain has been disturbed from its original position.
If a ___ pattern is found at a scene, it may show movement, lead to a discarded weapon, or provide identification of the suspect by his or her own blood.
Trail
A(n)____ is created by contact between a bloody object and a surface
Transfer pattern
True or False: Each bloodstain pattern found at a crime scene should be noted, studied, and photographed
True
True or False: Footwear transfer patterns created by an individual who was running typically show imprints with more space between them compared to those of an individual who was walking
True
True or False: Harder and less porous surfaces result in less spatter, whereas rough surfaces result in stains with more spatter and serrated edges
True
True or False: The pointed end of a bloodstain always faces toward its direction of travel
True
True or False: the direction of a flow pattern may show movements of objects or bodies while the flow was still in progress or after the blood has dried
True
Bloodstain patterns may convey to the analyst the location and movements of ___ or ___ during the commission of a crime
Victims; suspects
The shape and size of the blank space, or ___. created when an object blocks the deposition of spatter onto a surface and is then removed may give a clue as to the size and shape of the missing object or person.
Void
Drip Trail Pattern
a pattern of bloodstains formed by the dripping of blood off a moving surface or person in a recognizable pathway separate from other patterns
Area of Convergence
a two-dimensional view of the intersection of lines formed by drawing a line through the main axis of at least two drops of blood that indicates the general area of the source of the blood spatter
Angle of Impact
angle at which blood strikes a target surface relative to the horizontal plane of the target surface
Violent contact between individuals at a crime scene frequently produces bleeding and results in the formation of ____.
bloodstain patterns
A drop of blood that strikes a surface at an angle of impact of approximately 90 degrees will be close to (elliptical, circular) in shape.
circular
The proper interpretation of bloodstain patterns necessitates carefully planned ___ using surface materials comparable to those found at the crime scene.
control experiments
Reconstructing the circumstances of a crime scene is a team effort that may include the help of law enforcement personnel, medical examiners, and ____
criminalists
The ___ and ___ of blood striking an object may be discerned by the stain's shape
directionality; angle of impact
When documenting bloodstain patterns, the ___ involves setting up a grid of squares of known dimensions over the entire pattern and taking overview, medium-range, and close-up photographs with and without the grid
grid method
Generally, bloodstain diameter (increases, decreases) with height._____
increases
The classification system of impact spatter is based on the size of drops resulting from the velocity of the blood drops produced, and patterns can be classified as ____, ___, or ___ impact spatter
low velocity, medium velocity, high velocity
Area of Origin
the location of the blood source viewed in three dimensions as determined by projecting angles of impact of individual bloodstains
the angle of impact of an individual bloodstain can be estimated using the ratio of ___ divided by ___
width, length
Transfer pattern
A bloodstain pattern created when a surface that carries wet blood comes in contact with a second surface. Recognizable imprints of all or a portion of the original surface or the direction of movement may be observed.
Flows
A bloodstain pattern formed by the movement of small or large amounts of blood due to gravity's pull.
Impact Spatter
A bloodstain pattern produced when an object makes forceful contact with a source of blood, projecting droplets of blood outward from the source.
Cast-off
A bloodstain pattern that is created when blood is flung from a blood-bearing object in motion onto a surface.
Low velocity spatter
An impact spatter pattern created by a force traveling at 5 ft/sec or less and producing droplets with diameters greater than 3 mm.
Medium velocity spatter
An impact spatter pattern created by a force traveling at 5-25 ft/sec and producing droplets with diameters between 1 mm and 3 mm.
The ____ is the point on a two-dimensional plane from which the drops originated
Area of Convergence
The ____ of a bloodstain pattern in a three dimensional space illustrates the position of the victim or suspect when the stain-producing event took place
Area of Origin
____ is the method used to support a likely sequence of events at a crime scene by the observation and evaluation of physical evidence and statements made by individuals involved with the incident
Crime scene reconstruction
A bloodstain pattern created by ___ features bubbles of oxygen in the drying drops and may be lighter in color when compared to impact spatter
Expirated blood
True or False: Characteristics of a cast-off pattern arc cannot give clues as to the kind of object that was used to produce the pattern
False
True or False: Forward spatter consists of the blood projected backward from the source, and back spatter is projected outward and away from the source
False
True or False: the velocity classification system is a good way to classify impact patterns and to determine the kind of force that produced them
False
Arterial Spray
A characteristic bloodstain pattern containing spurts that resulted from blood exiting under pressure from an arterial injury.
Crime Scene Reconstruction
A hypothesis of the sequence of events from before the crime was committed through its commission
Void
An area within a deposited spatter pattern that is clear of spatter, caused by an object or person blocking the area at the time of the pattern's deposition.
High-Velocity Spatter
An impact spatter pattern created by a force traveling at 100 ft/sec or faster and producing droplets with diameters less than 1 mm.
When an injury is suffered to an artery, the pressure of the continuing pumping of blood projects blood out of the injured area in spurts creating a pattern known as ____.
Arterial spray spatter
Back Spatter
Blood directed back towards the source of the force that caused the spatter.
Expirated blood pattern
Blood that is expelled out of the nose, mouth, or respiratory system as a result of air pressure and/or air flow.
Forward Spatter
Blood which travels away from the source in the same direction as the force which caused the spatter.
A(n) ____ pattern commonly originates from repeated strikes from weapons or fists and is characterized by an arc pattern of separate drops showing directionality
Cast-off
____ is the most common type of blood spatter found at a crime scene and is produced when an object forcefully contacts a source of blood
Impact spatter
Movement of a bloody object across a surface, (lightens, darkens) as the pattern moves away from the point of contact.
Lightens
The edges of a bloodstain generally ___ within 50 seconds of deposition and are left intact even if the central area of a bloodstain is altered by a wiping motion
Skeletonize
Satellite spatter
Small droplets of blood that are distributed around the perimeter of a drop or pool of blood that were produced as a result of the blood impacting the target surface.
The ___ method is used at the crime scene to determine the area of origin
String
