Blood Spatter Analysis

General Rules  Directionality of a blood drop while in flight is usually obvious from the geometry of its resulting bloodstain. The pointed end indicates the direction of travel prior to impact on a surface.

General Rules  The shape of a bloodstain is a function of the angle at which it impacts a surface. Perfectly round bloodstains result from a ninety degree impact. The angle of impact of an elliptical bloodstain may calculated from its length to width ratio.

 Impact spatter:  High velocity  Medium velocity  Low velocity  Cast off Pattern  From bloody object  Arterial Spurting  From artery  Transfer Pattern  Swipe  Wipe  Passive Pattern  Gravity alone

TARGET SURFACE TEXTURE  Bloodstains can occur on a variety of surfaces, such as carpet, wood, tile, wallpaper, clothing, etc…  The type of surface the blood strikes affects the amount of resulting spatter, including the size and appearance of the blood drops.

TARGET SURFACE TEXTURE  Blood droplets that strike a hard smooth surface, like a piece of glass, will have little or no distortion around the edge.

General Rules  Surface tension prevents spattering regardless of the distance a drop of blood has fallen before impacting a smooth, hard surface such as glass.

TARGET SURFACE TEXTURE  Blood droplets that strike a fairly hard surface.. From a distance. Will show a distinct appearance. (scalloping) around the edge of the blood droplets.  And rays  And satelite drops

TARGET SURFACE TEXTURE  Surfaces such as wood or concrete are distorted to a larger extent. Notice the spines and secondary spatter present.

 Non spatter:  Transfer patterns  Swipe  wipe  Passive  Gravity only  Changes with time  Settle  Clot  Dry

Dried blood

Clotted Blood

Blood Drip

TRANSFER BLOODSTAINS  Swipe: A transfer bloodstain is created when a wet, bloody object comes in contact with a secondary surface.  Wipe: An object moves through an existing stain.

TRANSFER BLOODSTAINS: Swipe

Transfer pattern: wipe

PASSIVE BLOODSTAINS  Passive Bloodstains are drops created or formed by the force of gravity acting alone.

Spatter: PROJECTED BLOODSTAINS  Projected bloodstains are created when a blood source (victim) is subjected to a force  The size, shape, and number of resulting stains will depend, primarily, on the amount of force utilized to strike the blood source.

SPATTER Patterns  Spatter patterns  High velocity  Medium velocity  Low velocity  Arterial Spurting  Cast off

Arterial Spatter  Arterial Spurt / Gush  Bloodstain pattern(s) resulting from blood exiting the body under pressure from an artery (heart)

Cast Off Pattern  Cast-off Stains  Blood released or thrown from a blood- bearing object in motion

General Rules  The smaller the size of bloodspatters, the greater the energy required to produce them. Low, medium, and high velocity impact spatter may be identified by their respective sizes.

PROJECTED BLOODSTAINS - Impact  Low Velocity  Gravitational pull up to 5 feet/sec.  Relatively large stains 4mm in size and greater

General Rules  When the preponderance of individual bloodstains are approximately 1mm or more in diamerer, they have been produced by a medium velocity impact. Most often they would result from a beating or stabbing.

PROJECTED BLOODSTAINS - Impact  Medium Velocity  Force of 5 to 25 feet/sec.  Preponderant stain size 1 to 4mm in size

General Rules  When the preponderance of individual bloodstain diameters are less than 1mm, they have been produced as a result of a high velocity impact. Most often they would result from a shooting.

PROJECTED BLOODSTAINS - Impact  High Velocity  Force of 100 feet/sec. and greater  Preponderant stain size 1mm in size and smaller  Mist-like appearance