Forensic Science Blood Spatter Quest Review
Terms in this set (49)
What information can be gained from blood stain patterns?
- Mechanism of bloodstain pattern formation
- Position of people or objects
- Movement of people or objects
- Sequencing events
What are the two types of patterns?
Types of Non- Contact
Radial spatter patterns
Arc Patterns or "cast off"
Types of Contact
Footwear and fabric impression
Finger, hand and foot impressions
Smears and Smudges
Writing in blood
Two types of spatter
Back Spatter and Forward Spatter
What factors impact drying time?
- Surface ( Texture, Porosity)
- Environmental (Temperature, Humidity, Air Circulation)
What factors impact drop size?
Drop Height and Impact Velocity
Low- stains are about 4 mm in size (Hammer)
Medium- stains are 1-4mm in size (Beating)
High- stains are less than 1mm in size (Gun shot, high powered machinery)
Drops created or formed by the force of gravity acting alone. Subdivided to include: drops, drip patterns & trails, pools and clots.
Created when a wet, bloody surface comes in contact with a secondary surface a recognizable image of all or a portion of the original surface may be observed in the pattern
Ex. As in the case of a bloody hand or footwear
Created when an exposed blood source is subjected to an action or force, greater than the force of gravity \ (internally or externally produced).
Projected Bloodstains Subcategories
Arterial Spurt/ Gush
Resulting from blood exiting the body under pressure from a severed artery
Blood released or thrown from a blood- bearing object in motion
Created when a blood source receives a blow or force resulting in the random dispersion of smaller drops of blood
Arterial Spurting Pattern
Bloodstain patterns resulting from blood exiting the body under pressure from a breached artery
Blood directed back towards the source of energy or force that caused the spatter
Evidence that liquid blood has come in contact with a surface
The direction of a bloodstain or a pattern which indicates the direction the blood was traveling when it impacted the target surface. Direction of a blood drop's flight can usually be established from the geometric shape (tail) of its bloodstain.
blood that is blown out of the nose, mouth, or a wound as a result of air pressure or air flow, which is the propelling force Results in stain size of <1 mm
a change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object
blood that travels in the same direction as the source of energy or force that caused the spatter
bloodstain pattern created when blood receives a blow or force resulting in the random dispersion of smaller drops of blood
Blood which has been reduced to a fine spray
A drop of blood form which a wave, cast-off, or satellite spatter
Passive Drop (Bleeding)
Bloodstain drop(s) formed by the force of gravity acing alone
Projected Blood Pattern
A bloodstain pattern that is produced by blood released under pressure as opposed to an impact, such as arterial spurting
small droplets of blood distributed around a drop or pool of blood as a result of the blood hitting the target surface
A bloodstain that consists of only its outer periphery, the central area having been removed by wiping or flaking after liquid blood has partially or completely dried
That blood which has been dispersed as a result of force applied to a source of blood.
The pointed or elongated stains which radiate away from the central area of a bloodstain
the transfer of blood from a moving source onto an unstained surface; the direction of travel may be determined by the feathered edge
A bloodstain pattern created when a wet, bloody surface comes in contact with a second surface. A recognizable image of all or portion of the original surface may be observed in the pattern.
An absence of strains in an otherwise continuous bloodstain pattern
Pattern created when an object moves through an existing stain, removing/altering its appearance.
Who is the director of the Institute of the Physical Significance of Human Bloodstain Evidence (Blood School)?
Herbert Leon MacDonnel
Where is the institute held?
What cases has the director testified in?
Robert F. Kennedy, MLK, Black Panther Case, O.j Simpson
What disciplines has he given expert testimony on?
Fingerprint ID, firearms, crime scene reconstruct, forensic photo, Breathalyzer
What forensic tool did he patent? What is the tool especially good for?
Magna Brass, good to dust prints
What law of physical science will the behavior of blood follow?
Ballistics- projectiles in motion
What is the shape of a drop of blood? Why?
Sperical because it reaches equilibrium in mid air and gravity and force will make an equal force.
What is its typical volume?
What is its terminal velocity?
What kind of blood is used for the experiments at the school? Where do they get it from?
Human Blood, Red Cross
Why is a dead body turned to its back at a case?
Out of respect
What is a tadpole? (Blood)
Type of bloodstain (Length is greater than the width)
What is a cast-off? (Blood)
Object is swung in an arc and flings blood to nearby surfaces
Blood that has been blown, wheezed or sneezed looks like what?
A gunshot splatter