FBI Forensic Science Communications
Scientific Working Group on Bloodstain Pattern Analysis (SWGSTAIN)
This document provides a recommended list of terms to use when teaching, discussing, writing, or testifying on bloodstain pattern analysis.
The Scientific Working Group on Bloodstain Pattern Analysis (SWGSTAIN) comprises bloodstain pattern analysis (BPA) experts from North America, Europe, New Zealand, and Australia. SWGSTAIN provides a professional forum in which practitioners in BPA and related fields can discuss and evaluate methods, techniques, protocols, quality assurance, education, and research. SWGSTAIN’s ultimate goal is to use these professional exchanges to address substantive and operational issues within the field of BPA and to build consensus-based, or “best practice,” guidelines for the enhancement of the discipline of BPA.
SWGSTAIN has developed and defined a list of recommended terminology for use in BPA. In developing this list, SWGSTAIN reviewed terminology in use across BPA.
A small blood drop produced as a by-product of drop formation.
A bloodstain with characteristics that indicate a physical change has occurred.
Angle of Impact
The acute angle (alpha), relative to the plane of a target, at which a blood drop strikes the target.
Area of Convergence
The area containing the intersections generated by lines drawn through the long axes of individual stains that indicates in two dimensions the location of the blood source.
Area of Origin
The three-dimensional location from which spatter originated.
A bloodstain pattern resulting from blood drops that traveled in the opposite direction of the external force applied; associated with an entrance wound created by a projectile.
A gelatinous mass formed by a complex mechanism involving red blood cells, fibrinogen, platelets, and other clotting factors.
A deposit of blood on a surface.
A grouping or distribution of bloodstains that indicates through regular or repetitive form, order, or arrangement the manner in which the pattern was deposited.
An outline within a bloodstain resulting from air in the blood.
A bloodstain pattern resulting from blood drops released from an object due to its motion.
Cessation Cast-off Pattern
A bloodstain pattern resulting from blood drops released from an object due to its rapid deceleration.
The characteristic of a bloodstain that indicates the direction blood was moving at the time of deposition.
The angle (gamma) between the long axis of a spatter staintarget. and a defined reference line on the
A bloodstain pattern resulting from a liquid that dripped into another liquid, at least one of which was blood.
A bloodstain resulting from a falling drop that formed due to gravity.
A bloodstain pattern resulting from the movement of a source of drip stains between two points.
A physical feature of the periphery of a bloodstain.
A bloodstain pattern resulting from blood forced by airflow out of the nose, mouth, or a wound.
A bloodstain pattern resulting from the movement of a volume of blood on a surface due to gravity or movement of the target.
Forward Spatter Pattern
A bloodstain pattern resulting from blood drops that traveled in the same direction as the impact force.
A bloodstain pattern resulting from an object striking liquid blood.
A bloodstain resulting from insect activity.
A bloodstain pattern resulting from blood reduced to a spray of micro-drops as a result of the force applied.
A bloodstain from which a satellite stain originated.
An altered stain that consists of the peripheral characteristics of the original stain.
A bloodstain resulting from an accumulation of liquid blood on a surface.
A bloodstain pattern resulting from the ejection of a volume of blood under pressure.
A smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface.
A bloodstain resulting from the accumulation of liquid blood in an absorbent material.
The stain resulting from the liquid portion of blood (serum) that separates during coagulation.
A bloodstain resulting from a blood drop dispersed through the air due to an external force applied to a source of liquid blood.
A bloodstain pattern resulting from a volume of liquid blood that falls or spills onto a surface.
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.
A surface onto which blood has been deposited.
A bloodstain resulting from contact between a blood-bearing surface and another surface.
An absence of blood in an otherwise continuous bloodstain or bloodstain pattern.
An altered bloodstain pattern resulting from an object moving through a preexisting wet bloodstain.