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Cartes-fiches
Define "bloodstain pattern analysis" (1p)
Bloodstain pattern analysis: the study of the shapes, sizes, and locations of bloodstains in order to determine the physical events that gave rise to their origin
Describe the work of Dr. Eduard Piotroski (4p)
1. Studied at the Institute of Forensic Medicine, Krakow Poland, and first significant study published in 1985
2. Concerning the Origin, Shape, Direction, and Distribution of the Bloodstains, Following Head Wounds, Caused by Blows
3. 1955 - significant milestone in the use of bloodstain evidence in the legal system
4. Dr. Paul Kurk of the University of California issued a report regarding his findings based upon bloodstain evidence to the Court of Common Pleas in the case of the State of Ohio vs. Dr. Sheppard ("The Figuitive"(
Describe the work of Dr. Eduard Piotroski (4p)
1. Studied at the Institute of Forensic Medicine, Krakow Poland, and first significant study published in 1985
2. Concerning the Origin, Shape, Direction, and Distribution of the Bloodstains, Following Head Wounds, Caused by Blows
3. 1955 - significant milestone in the use of bloodstain evidence in the legal system
4. Dr. Paul Kurk of the University of California issued a report regarding his findings based upon bloodstain evidence to the Court of Common Pleas in the case of the State of Ohio vs. Dr. Sheppard ("The Figuitive"(
List 10 possible types of information that may be found through bloodstain pattern analysis (10p)
1. Origin of bloodstain
2. Location of original blow
3. If an artery was cut
4. Distances beween impact areas of blood spatter and origin
5. Type and direction of impact that produced the bloodstain
6. Object that produced the particular bloodstain pattern
7.Number of blows/shots that occurred
8. Position of victims, assailant, and/or objects while they were shedding blood
9. Support or contradict statements given by suspect or witness
10. Correlation with other pathology of laboratory finding releveant to the investigation
THe ultimate goal of bloodstain pattern analysis is to reconstruct the crime scene. What are 5 questions that must be addressed? (5p)
1. What events occurred?
2. When and what sequence did occur?
3. Who was there when it occurred?
4. Who was not there during each event?
5. What did not occur?
What are the 4 basic tenets of bloodstain pattern analysis? (4p)
1. Blood will behave according to the laws of physics
2. The size of a projected bloodstain has a direct relationship to the speed at which it is travelling
3. The direction of a bloodstain may be determined by analyzing its shape
4. Bloodstain patterns are predictable and reproducible
Define "surface tension" (1p)
Surface tension: the force that pulls the surface molescules towards the interior of the liquid of a fluid and decreases the surface area (force per unit length)
What shape do droplets in liquids assume? How does a larger surface area translate in terms of tension? (2p)
1. Spherical in air
2. Larger surface area = greater tension
Define "viscosity" - of a liquid (1p) and what, in blood, it is most affected by (2p)
1. Viscosity: resistance to change of form or flow due to the mutual attraction of molecules to each other
2. Viscosity is greatly increase due to clotting
What is the equation for determining the angle of impact? Describe the shape of a bloodstain with an AOI at 10° vs that of one at 90° (3p)
1. Angle of impact = Sin-1 (Width/Length)
2. AOI = 10° = more elliptical shape
2. AOI = 90° = more circular shape
What is one requirement in using the formula for determining the AOI? (1p)
The formula for angle of impact can only be used on a right-angle triangle
In which direction does scalloping occur? (1p)
Scalloping occurs for the direction that the blood source is moving in
How is the point or area of convergence determined? (1p)
The point or area of convergence is determined by tracing the long axis of well-defined bloodstains within the pattern back to a common point, usually using strings and/or lasers
What do several points or areas of convergence represent? (1p)
Multiple impact sites and/or movement
Define "point/area of convergence" (1p)
The location in space from which the blood that produced the bloodstain originated from
Define "point/area of convergence" (1p)
The location in space from which the blood that produced the bloodstain originated from
Describe the use of the "tangent method" for determining the area of origin (AOO) (4p)
1.Determine the area of impact (AOI)
2. Determine the point of convergence (POC) through long axis
3. Measure distance from base of individual bloodstain to POC (A)
4. Calculate AOO = A Tan(AOI)
How does force correlate with stain size? (1p)
The higher the force, the smaler the stain size
Define the adjective "skeletonized" in terms of bloodstains (1p)
Skeletonized: the disturbance or effect of someone or something having walked through or rubbed partially dried blood, resulting in some blood being trasferred from the original stain
Define "satellite spatter" in terms of blood spatter analysis (1p)
Satellite spatter: extra blood that is either displaced from the main pooling when more blood drips into the pool, or generally any extra blood coming off from the sides of the main pool
How does surface texture affect the appearance of bloodstains? (2p)
The degree of distortion and spattering from freefall is a function of surface texture rather than height.
1. Smooth-hard = uniform, circular stains
2. Rough-textured or porous = exhibits distortion, irregular shape, spiny edges (eg, wood, cardboard, concrete)
What are the most important characteristics of spill pattern vs pool pattern? (2p)
1. Spill pattern - sudden, high amount of blood spilling
2. Pool pattern - large amount of blood to one spot, adhesion to surface
How is the resulting diameter of a blood drop related to the height from which it had dropped? (2p)
1. As the height of free-fall increases, the diameter increases
2. Beyond 6-7ft, there is no appreciable increase in diameter
What do "clear" edges on drying or dried blood indicate? (1p)
The presence of blood plasma or blood serum
Describe low-velocity impact blood spatter (5p)
1. Free-falling drops, pools, transfer patterns, satellite spatter, cast-off, swipes, wipes
2. External force of less than 5fps
3. Stains genenrally 3mm or larger
4. Directionality can be determined by shape
5. Free-fall = less than 90 degrees, walking = <90 degrees
How does satellite spatter occur, what does it normally look like, and what are some factors affecting it? (3p)
1. Satellite spatter is a type of drip pattern sulting from blood drops falling into pooled blood
2. Small droplets of blood that had detached from the main blood volume at the moment of impact, occurring around the periphery of the central stain
3. Factors affecting satelite spatter are blood drop volume, freshness, and surface texture
How does cast-off spatter occur, what is the degree at which it is observed on walls and ceilings perpendicular to the assailant, and what are factors in the blood stain pattern? (3p)
1. Cast-off spatter is the result of centrifugal force as the weapon is swung back over the attacker's head
2. 90 degrees at the wall and ceiling (round stains) with the remainder of bloodstains being oval-shaped due to angular impact
3. Bloodstains relative to the type of weapon, amount of blood, forcefulness, and length of arc of swing
Describe medium-velocity impact (6p)
1. Resulting from blunt-force trauma - beating with fists, bats, bricks, hammers, etc.
2. External force of 5-25fps
3. Typical bloodstain size of 1-3mm
4. Surface tension is severed, and blood is broken up into many drops
5. Radial patterns are common and distributed like spokes of a wheel
6. Misting generally stays down low
Describe high-velocity impact (4p)
1. Resulting from gunshots, explosions, power tools, machinery, etc.
2. External force applie to blood source greater than 100fps
3. Bloodstains produced are less than 1mm, and may be referred to as "misting"
4. Bloodstains travel the least distance from the bloodsource due to small mass
Describe the type of spatter occurring from gunshot, and 5 factors to be considered (3p)
1. Blood spatter being thrown back towards the gun which had created the wound entrance - may be absent if the gun used is of considerable distance
2. Blood spatter exiting the same direction as the bullet from the exit wound
3. Amount of spatter depends on the type of weapon, ammunition style, whether the muzzle was directly on the target, hair, and type of clothing
How is arterial gushing characterized and from what cause? (3p)
1. Appears as clusters of large stains and flow patterns
2. Blood exits the body under pressure as a result of a cut or breached artery
3. Fluctuations of arterial pressure may be identified
Define: swipe (1p)
Swipe: blood transferred to a surface as a blood-soaked object is moved along that surface
Define: wipe (1p)
Wipe: a previously existing bloodstain having an object passed through it on the surface, thus disrupting the patttern
Define: void (1p)
Void: the absence of blood in an otherwise continuous bloodstain due to the presence of one or more intervening objects
