Blood Spatter Analysis Exam Study Guide |
Questions with 100% Correct Answers
Blood stain pattern interpretation may uncover: (6) - Answer 1. The direction from
which blood originated. 2. The angle at which a blood droplet struck a surface. 3. The
location or position of a victim at the time a bloody wound was inflicted. 4. The
movement of a bleeding individual at the crime scene. 5. The approximate number of
blows that struck a bleeding victim. 6. The approximate location of an individual
delivering blows that produced a bloodstain pattern
What can a blood pattern tell us at the scene (8) - Answer 1. Position of victim and
offender and/or objects at time of bloodshed 2. movement of persons and/or objects
around a crime scene 3. was there a fight or struggle 4. possible type of weapon used 5.
minimum number of blows, shots/actions 6. possible offender injuries 7. amount and
nature of blood staining on assailant 8. has anyone attempted to clean up?
What can a blood pattern tell us on clothing ( 2) - Answer 1. actions of the individual
wearing the clothing 2. position of the individual wearing the clothing when the blood
was deposited
What can a blood pattern tell us on weapons/objects - Answer 1. was the item used as a
weapon or was it just present when blood was shed. 2. was the item moved after blood
was deposited? 3. was an attempt made to clean the item
Directionality of a blood stain can be determined: - Answer The pointed end of a
bloodstain always faces its direction of travel.
Impact angle- determined by measuring what? - Answer The impact angle of blood on a
flat surface can be determined by measuring the degree of circular distortion. At right
angles the blood drop is circular; as angle decreases, the stain becomes elongated.
, When does the elongation of a droplet occur? - Answer The elongation of a droplet
occurs on impact
Angle of incidence - Answer The angle of incidence is the angle at which a blood droplet
impacts a surface, measured with respect to an imaginary line perpendicular to that
surface. At 0 the blood droplet is perfectly circular. at 80 degrees it is extremely elliptical
in shape.
How to determine the angle of incidence mathmatically - Answer The major (long) and
minor (short) diameters of the stain are measured and the ratio of the minor to major
dimensions is calculated. The ratio value equals the cos of the angle of incidence.
cos(angle) = minor d / major d
Impact bloodstain spatter patterns - Answer Impact spatters occurs when an object
impacts a source of blood.
Forward spatter - Answer projected outward and away from the source
back spatter - Answer also known as blow back spatter is projected backward from the
source
Classifying Impact Spatter - Answer Use droplet size to classify impact patterns by
velocity gives investigators insight into the general nature of a crime but cannot
illuminate the specific events that produced the spatter pattern (LOW, MEDIUM, HIGH)
Low velocity patterns - Answer Drops with diameters of 4mm or more normally
produced by an applied force of up to 5 ft/sec. Formed by blood falling onto a surface
influenced only by the force of gravity. Typically dripping patterns.
Questions with 100% Correct Answers
Blood stain pattern interpretation may uncover: (6) - Answer 1. The direction from
which blood originated. 2. The angle at which a blood droplet struck a surface. 3. The
location or position of a victim at the time a bloody wound was inflicted. 4. The
movement of a bleeding individual at the crime scene. 5. The approximate number of
blows that struck a bleeding victim. 6. The approximate location of an individual
delivering blows that produced a bloodstain pattern
What can a blood pattern tell us at the scene (8) - Answer 1. Position of victim and
offender and/or objects at time of bloodshed 2. movement of persons and/or objects
around a crime scene 3. was there a fight or struggle 4. possible type of weapon used 5.
minimum number of blows, shots/actions 6. possible offender injuries 7. amount and
nature of blood staining on assailant 8. has anyone attempted to clean up?
What can a blood pattern tell us on clothing ( 2) - Answer 1. actions of the individual
wearing the clothing 2. position of the individual wearing the clothing when the blood
was deposited
What can a blood pattern tell us on weapons/objects - Answer 1. was the item used as a
weapon or was it just present when blood was shed. 2. was the item moved after blood
was deposited? 3. was an attempt made to clean the item
Directionality of a blood stain can be determined: - Answer The pointed end of a
bloodstain always faces its direction of travel.
Impact angle- determined by measuring what? - Answer The impact angle of blood on a
flat surface can be determined by measuring the degree of circular distortion. At right
angles the blood drop is circular; as angle decreases, the stain becomes elongated.
, When does the elongation of a droplet occur? - Answer The elongation of a droplet
occurs on impact
Angle of incidence - Answer The angle of incidence is the angle at which a blood droplet
impacts a surface, measured with respect to an imaginary line perpendicular to that
surface. At 0 the blood droplet is perfectly circular. at 80 degrees it is extremely elliptical
in shape.
How to determine the angle of incidence mathmatically - Answer The major (long) and
minor (short) diameters of the stain are measured and the ratio of the minor to major
dimensions is calculated. The ratio value equals the cos of the angle of incidence.
cos(angle) = minor d / major d
Impact bloodstain spatter patterns - Answer Impact spatters occurs when an object
impacts a source of blood.
Forward spatter - Answer projected outward and away from the source
back spatter - Answer also known as blow back spatter is projected backward from the
source
Classifying Impact Spatter - Answer Use droplet size to classify impact patterns by
velocity gives investigators insight into the general nature of a crime but cannot
illuminate the specific events that produced the spatter pattern (LOW, MEDIUM, HIGH)
Low velocity patterns - Answer Drops with diameters of 4mm or more normally
produced by an applied force of up to 5 ft/sec. Formed by blood falling onto a surface
influenced only by the force of gravity. Typically dripping patterns.
