Blood Pattern Analysis

Blood pattern analysis

The examination, identification and interpretation of bloodstains in relation to the actions that caused them

Spatter

A bloodstain resulting from a blood drop dispersed through the air due to an external force applied to a source of liquid blood

Impact spatter

bloodstain patterns created when a blood source receives a blow or force resulting in the random dispersion of smaller drops of blood

Cast off

blood release or throw from a bloody object

Arterial damage

blood pattern resulting from blood exiting the body under pressure from a breached artery

what kind of spatter? blunt force, gunshot, exhalation, splash

impact

what kind of spatter? drip, swing, cessation

cast off

what kind of spatter? gush, spurt, rain

arterial damage

3 types of non-spatter

transfer, physiologically altered bloodstains (PABS), volume

Pool

A bloodstain resulting from an accumulation of liquid blood on a surface

Void

An absence of blood in an otherwise continuous bloodstain (pattern)

Satellite stain

A smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface

Perimeter stain

An altered stain that consists of the peripheral characteristics of the original stain, which partially dried and then was wiped

which is the most common blood pattern?

impact spatter

How does cast-off happen?

Centrifugal force causes wet blood to pool at one end of the weapon. When momentum overcomes surface tension, the blood will be cast off from the surface

What’s the general/common appearance of a cast off pattern?

linear, the volume of the drops and their angle changes as the weapon goes through its motion

Cessation cast off pattern

A bloodstain pattern resulting from blood drops released from an object due to its coming to an abrupt halt

Drip pattern

A bloodstain pattern resulting from a liquid that dripped into another liquid, at least one of them being blood

what stains does the drip pattern create by definition?

satellite stains

Drip stain

a bloodstain resulting from a falling drop that formed due to gravity

Projected pattern

A bloodstain pattern resulting from the ejection of a volume of blood under pressure

Bubble ring

An outline within a bloodstain resulting from air in the blood

Expiration pattern

A bloodstain pattern resulting from blood forced by airflow out of the nose, mouth, or a wound

Flow pattern

A bloodstain pattern resulting from the movement of a volume of blood on a surface due to gravity or movement of the target

Swipe pattern

A bloodstain pattern resulting from the transfer of blood from a blood-bearing surface onto another surface, with characteristics that indicate relative motion between the two surfaces

Wipe pattern

An altered bloodstain pattern resulting from an object moving through a pre-existing wet bloodstain

Transfer stain

A bloodstain resulting from contact between a blood-bearing surface and another surface

what is this pattern called? why does it happen?

it’s spines, it happens because of surface texture

Saturation stain

A bloodstain resulting from the accumulation of liquid blood in an absorbent material

what are some physical factors to consider during BPA?

gravity, viscosity, surface tension, velocity