Mystery Writer's Guide to Forensic Science - Blood Patterns - Part 1 (Might be disturbing)

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Just a warning: The article below has photos with blood patterns. If that sort of thing bothers you, don't go on. Nothing Gory. No dead bodies.

When a violent crime is being committed, most of the time, blood is left behind. How do forensic scientists classify and analyze these stains?

Passive bloodstains - are those stains created by the force of gravity.

Drip Pattern

Drop Pattern

Passive Drops - Bloodstain drop(s) created or formed by the force of gravity acting alone.
Drip Pattern - A bloodstain pattern which results from blood dripping into blood.
Flow Pattern - A change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object.
Pool Pattern - A bloodstain pattern formed when a source of blood is stationary for a period of time.

Angles of Inpact

Transfer/Contact bloodstains - A transfer or contact stain is produced when an object with blood comes in contact with an object or surface that does not have blood. It may be possible to discern the object that left the blood impression.

Blood Transfer by Hand

Wipe Pattern - A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance.
Swipe Pattern - The transfer of blood from a moving source onto an unstained surface. Direction of travel may be determined by the feathered edge.

Projected bloodstains - this occurs when some form of energy has been transferred to a blood source. (We'll look at those in more detail next week)

Terminology

Angle of Impact -- The acute angle formed between the direction of a blood drop and the plane of the surface it strikes.

Bloodstain -- Evidence that liquid blood has come into contact with a surface.

Bubble Rings -- Rings in blood that result when blood containing air bubbles dries and retains the bubble's circular configuration as a dried outline.

Directionality -- The directionality of a bloodstain or pattern which indicates the direction the blood was traveling when it impacted the target surface. Directionality of a blood drop's flight can usually be established from the geometric shape of its bloodstain.

Directionality Angle -- The angle between the long axis of a bloodstain and a predetermined line on the plane of the target surface which represents 0 degrees.

Drip Pattern -- A bloodstain pattern which results from blood dripping into blood.

Flight Path -- The path of the blood drop, as it moves through space, from the impact site to the target.

Flow Pattern -- A change in the shape and direction of a bloodstain due to the influence of gravity or movement of the object.

Parent Drop -- A drop of blood from which a wave, cast-off, or satellite spatter.

Passive Drop (Bleeding) -- Bloodstain drop(s) created or formed by the force of gravity acting along.

Point (Area) of Convergence -- The common point (area), on a two dimensional surface, over which the directionality of several blood drops can be retraced.

Point (Area) of Origin -- The common point (area) in a three dimensional space to which the trajectories of several blood drops can be retraced.

Satellite Spatter -- Small droplets of blood that are distributed around a drop or pool of blood as a result of the blood impacting the target surface.

Perimeter Stain -- 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.

Spine -- The pointed or elongated stains which radiate away from the central area of a bloodstain.

Swipe Pattern -- The transfer of blood from a moving source onto an unstained surface. Direction of travel may be determined by the feathered edge.

Target -- A surface upon which blood has been deposited.

Transfer/Contact Pattern -- 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.

Void -- An absence of strains in an otherwise continuous bloodstain pattern.

Wave Cast-Off -- A small blood drop that originates from a parent drop of blood due to the wave-like action of the liquid in conjunction with striking a surface.

Wipe Pattern -- A bloodstain pattern created when an object moves through an existing stain, removing and/or altering its appearance.


Sources:
1) Wikipedia
2) Suite 101
3) Chem Matters
4) ezine
5) bloodspatter.com
6) Blood spatter video (very interesting - not gory)