FRSC 2101 Classifying Bloodstain Patterns

Spurt

Stains created when blood is ejected in a stream under pressure or with velocity, most often encountered when an artery or the heart is breached

Cast-off

Stains created when blood is flung from an object that is either in motion or which suddenly stops some motion

Drip Trail

A pattern of individual spatter deposited on a surface, demonstrating movement of the dripping item from one point to another

Impact

A radiating pattern of small circular or elliptical shaped stains created when blood is broken up at a source by some force

Drip(s)

Spatter resulting from blood dripping from an individual or otherwise bloodied object

Gush/Splash

An irregular pattern created when blood is ejected in volume

Blood into Blood

A pattern of spatter deposited into one another or into another liquid, resulting in an accumulation and secondary spatter randomly oriented around the stain

Smear

Any stain or pattern created by the transfer of blood from one object onto another, through some form of contact

Pattern Transfer

Any stain or pattern created by the transfer of blood from one object to another in which a recognizable characteristic or image is present in the pattern

Saturation stains

Occur when blood is drawn into clothing, cloth, or permeable surfaces

Fly spot patterns

Resulting patterns can mimic to some degree impact spatter, appearing as a number of small circular stains; in some instances, they may also mimic directional spatter

Mist

Majority of the stains present are smaller than 1-mm

Expiratory spatter

Mixtures of blood and small air bubble created as a result of the breathing of a victim

Wipe

A smear through a pre-existing stain or pattern

Swipe: A smear where the blood is deposited onto the surface

A smear where the blood is deposited onto the surface

Spurt (linear)

• A series of related spatter stains in a linear or curvilinear orientation

• A large volume is evident in the individual stains, demonstrated by flows from individual stains or a large volume in the overall pattern

• Any of the following:

  • Lines of stains or overlapping stains deposited in V’s, arcs, or a serpentine pattern

  • Large elliptical stains

Cast-off (linear)

• A series of related spatter stains

• Deposited in a linear or curvilinear orientation

• With consistent parallel directional angles in the stains to the overall pattern

• A consistent change in impact angle in the pattern

Drip Trail (linear)

• In-line distribution of spatter stains

• Consistent stain size range in the pattern, relative to any change in surface characteristics or decreasing volume available to produce the drip

• The stains lead from one point to another

• Stains will typically range in size between 3– to 25-mm

• The directional angle must be consistent with gravitational force

Impact Pattern (non-linear)

• A series of related small spatter stains

• Deposited in a pattern that has a radiating distribution in some fashion

• With a progressive change in individual stain shape the further out in the pattern

• Various size range of parent stains, but generally consistent throughout the pattern

• Occur primarily where a blood source is displaced by an impact of some nature (e.g., gunshot or blunt trauma

• Individual size of the spatter stains typically ranges from small sub-millimeter stains up to larger 4- to 5-mm stains

Drip(s) (non-linear)

• One or more spatter stains

• Parent stains have a generally large diameter (typically 3- to 25-mm)

• Randomly oriented on a surface

• The directional angle must be consistent with gravitational force

Gush/Splash (irregular margin)

• A large volume accumulation evident in the overall pattern

• Large irregular margin stain exhibiting spines and satellite spatter radiating from it

• There may be large elliptical spatter stains around the pattern

Blood into Blood (irregular margin)

• A pooling of blood or some combination of blood and some other liquid which may exhibit evidence of overlapping drips

• Surrounded by a random distribution of small satellite spatter

• These surrounding satellite spatter will show highly random variation in their directional angles and shapes

Smear (irregular margin)

• An irregular margin stain

• Demonstrating any of the following:

  • A contiguous boundary

  • A feathered boundary

  • Striations in the body of the stain

  • Diminished volume of blood across the body of the stain

  • Evident displacement of blood

Pattern Transfer (regular margin)

• A contact pattern

• Demonstrating angular demarcations, curves or other recognizable characteristics or an image of the source object

• It may be deposited in a series

The Pattern Diversity Principle

"The variations in combinations of blood volumes and forces acting on those volumes lead to recognizable classes of patterns."

The Principle of Stain Shape and Vector Correlation

"The shape of certain bloodstains provides indicators as to the direction of deposition as well as to the spatial origin of the blood."

Directional Angle

• Determined based on:

  • Collapse of the fluid droplet

  • Resulting long axis of the stain

  • Creation of scallops, tails, and satellite stains that appear on or around the stain