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Forensics Chapter 4

Key Concepts:

Terms in this set (63)

The skeletonized perimeter of a bloodstain can be used to interpret:
The source of the bloodstain, the time that elapsed between deposition of the stain and alteration of the stain.
A blood droplet deposited at an angle of impact of about 90 degrees°(directly vertical to the surface) will:
Be approximately circular in shape
The velocity at which blood strikes a surface is not useful to describe the specific events that produced the spatter pattern. (T/F)
True
Void spatter is the most common type of bloodstain pattern found at a crime scene. (T/F)
False
Setting up squares of known dimension over the entire pattern describes the:
Grid Method
The direction of a ________ may show movements of objects or bodies while the pattern was still forming or after the blood has dried.
Flow Pattern
Gunshot exit wounds commonly produce medium-velocity spatter, while explosions produce high−velocity Spatter. (T/F)
False
The removal of an object or surface that was located between the origin of blood and the target surface during the bloodstain deposition leaves behind:
A void
Droplets of ________ are very small. They may not travel far and could be overlooked.
High velocity splatter
Crime scene reconstruction requires the piecing together of:
Accounts given by the witnesses and suspects, the story told by evidence recovered at the crime scene and the input from the medical examiner.
The intersection of straight lines through the long axis of several individual bloodstains in an impact spatter pattern illustrates the ________ of the pattern.
Area of convergence
Widely spaced bloody shoeprints with satellite spatter between the shoeprints were likely deposited by an individual who was:
Running
The location of injury, the size of the wound created, the distance between the victim and the muzzle of the weapon all affect the amount of backward spatter that occurs. (T/F)
True
What should one surmise if a flow found on an object or body does not appear consistent with the direction of gravity?
The object or body was moved after the blood had dried.
An impact pattern consisting of large separate drops with diameters of 5 millimeters is:
Low velocity splatter
If a murder victim's blood is found in the muzzle of a firearm:
It can be concluded that the firearm was present during injury to the victim.
The less blood on an object, the smaller the stains produced. (T/F)
True
Physical evidence that can be used to aid in a crime scene reconstruction includes:
Gunshot residues, glass fragments and blood spatters
The presence of a cast-off pattern shows that there were more than ________ blow(s) delivered:
One
The sizes of the drops in a cast-off pattern are not related to the size of the point from which they were propelled. (T/F)
False
Forward spatter is more likely to be deposited on the object or person creating the impact. (T/F)
False
Proper location and documentation of bloodstain patterns at the crime scene is the responsibility of:
All crime scene personnel.
The pointed end of a bloodstain always faces its direction of travel. (T/F)
True
Rough surfaces usually result in stains with:
Satellite spatter
The pressure of the pumping of oxygenated blood out of an injury causes bright red-colored blood to spurt out and form a(n):
Arterial spray pattern
The amount of spatter from a blood droplet falling on a hard, non-porous surface is ________ that of a drop of blood of equal size, falling from the same distance, onto a softer, porous surface.
Less than
During crime scene reconstruction, no evidence or data should ever be excluded. (T/F)
True
At the crime scene, the string method is used to find the ________ of an impact spatter pattern.
Area of origin
The tails of the drops in a trail pattern point in the direction that the person was moving (T/F)
True
Crime scene reconstructions have the best chance of accuracy if:
Investigators use proper documentation and collection methods for all types of evidence
In the grid method of bloodstain documentation, a grid of squares of known dimensions is created over an entire pattern in order to:
Show the relative sizes of bloodstains in photographs
Setting up a rectangular border of rulers around the patterns and then placing a small ruler next to each stain describes the:
Perimeter ruler method
A blood stain that impacts a surface at a low angle will have a ________ tail than one that impacts at a higher angle.
Longer
Drops propelled from a blunt surface will be larger and the pattern will be:
Wide
The process of crime scene reconstruction may enlist the expertise of all of the following EXCEPT:
A criminal personality profiler
Crime scene reconstruction involves the efforts of all EXCEPT the:
Trial judge
The first transfer pattern will be lighter in color while subsequent transfers will be increasingly dark and heavy. (T/F)
False
The most common type of bloodstain pattern found at a crime scene is:
Impact spatter
Expirated blood is blood that is expelled from the mouth or nose from an external injury. (T/F)
False
The approximate drying time of a pool of blood can be used to estimate timing of events at a crime scene and is dependent upon:
The environmental condition of the scene
By counting and pairing the patterns of a(n) ________ pattern, an investigator can estimate the minimum number of blows inflicted upon a victim.
Cast off
The pointed end of a bloodstain always faces:
Its direction of travel
A trail pattern leading away from the victim at a stabbing scene was most likely created by:
Blood dripping from the murder weapon
Which of the following is of paramount importance in the interpretation of bloodstain patterns?
The surface texture
The flow pattern on an object or body can help determine if the body was moved after the blood had dried. (T/F)
True
Drops propelled from a small or pointed surface will be smaller and the pattern more linear. (T/F)
True
Voids may help investigators establish the body position of the victim or assailant at the time of the incident. (T/F)
True
What information can an investigator gain from the location of the area of origin of a bloodstain pattern?
Position of the person form which the pattern originated.
Generally, bloodstain diameter ________ as height increases.
Increases
A flow pattern is created when an object blocks the deposition of blood spatter onto a target surface or object. (T/F)
False
Back spatter consists of the blood projected backward from the source. (T/F)
True
________ transfer patterns are produced when the object makes contact with the surface and the object is removed without any movement.
Simple
Since droplets of high-velocity spatter are very small, they may not travel far. (T/F)
True
Pools of blood are not reliable to use in reconstruction or determining the amount of time that has elapsed since the blood was deposited. (T/F)
False
A bloodstain that impacts a surface at a low angle with have a shorter tail than one that impacts at a higher angle. (T/F)
False
When an object with blood on it touches one that does not have blood on it, this produces a(n):
Contact pattern
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
Which weapon would create cast-off patterns consisting of small droplets in a linear pattern?
Knife
In general, as both the force and velocity of impact increase, what happens to the diameter of the resulting blooddroplets?
Decreases
In general, as both the force and velocity of impact increase, the diameter of the resulting blood droplets increases. (T/F)
False
The velocity classification of an impact spatter pattern:
Cannot illuminate the specific event that produced the pattern
The deposition of backward spatter produced by a gunshot wound is determined by:
The distance between the victim and the muzzle, the size of the wound created and the location of the injury.
When an object blocks the deposition of blood spatter onto a target surface or object, the result is a:
Void pattern
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