Blood pattern analysts use a number of terms to describe bloodstains, how they behave and the methodology of examining a scene for blood evidence. The glossary terms below are from the Scientific Working Group on Bloodstain Pattern Analysis (SWGSTAIN).
Angle of Impact - The angle at which a blood drop strikes a surface.
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 blood spatter originated.
Backspatter Pattern - 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.
Blood Clot - A gelatinous mass formed by a complex mechanism involving red blood cells, fibrinogen, platelets, and other clotting factors.
Bloodstain - A deposit of blood on a surface.
Bloodstain Pattern - A grouping or distribution of bloodstains that indicates through regular or repetitive form, order, or arrangement the manner in which the pattern was deposited.
Bubble Ring - An outline within a bloodstain resulting from air in the blood.
Cast-off Pattern - 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.
Drip Pattern - A bloodstain pattern resulting from a liquid that dripped into another liquid, at least one of which was blood.
Drip Stain - A bloodstain resulting from a falling drop that formed due to gravity.
Drip Trail - A bloodstain pattern resulting from the movement of a source of drip stains between two points.
Edge Characteristic - A physical feature of the periphery of a bloodstain.
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.
Forward Spatter Pattern - A bloodstain pattern resulting from blood drops that traveled in the same direction as the impact force.
Impact Pattern - A bloodstain pattern resulting from an object striking liquid blood.
Luminol (C8H7N3O2) - is a versatile chemical that exhibits chemiluminescence, with a striking blue glow, when mixed with an appropriate oxidizing agent. Luminol is used by forensic investigators to detect trace amounts of blood left at crime scenes as it reacts with iron found in hemoglobin.
Mist Pattern - A bloodstain pattern resulting from blood reduced to a spray of micro-drops as a result of the force applied.
Parent Stain - A bloodstain from which a satellite stain originated.
Perimeter Stain - An altered stain that consists of the peripheral characteristics of the original stain.
Plasma - The clear, yellowish fluid portion of blood.
Platelet - An irregularly shaped cell-like particle in the blood that is an important part of blood clotting. Platelets are activated when an injury causes a blood vessel to break. They change shape from round to spiny, “sticking” to the broken vessel wall and to each other to begin the clotting process.
Pool - A bloodstain resulting from an accumulation of liquid blood on a surface.
Projected Pattern - A bloodstain pattern resulting from the ejection of a volume of blood under pressure, such as a spurt or spray.
Satellite Stain - A smaller bloodstain that originated during the formation of the parent stain as a result of blood impacting a surface.
Saturation Stain - A bloodstain resulting from the accumulation of liquid blood in an absorbent material.
Serum Stain - The stain resulting from the liquid portion of blood (serum) that separates during coagulation.
Spatter Stain - A bloodstain resulting from a blood drop dispersed through the air due to an external force applied to a source of liquid blood.
Spines - A bloodstain feature resembling spokes or rays emanating out from the edge of a blood drop; they result from the drop contacting a non-smooth surface.
Splash Pattern - A bloodstain pattern resulting from a volume of liquid blood that falls or spills onto a surface.
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.
Transfer Stain - A bloodstain resulting from contact between a blood-bearing surface and another surface.
Void - An absence of blood in an otherwise continuous bloodstain or bloodstain pattern.
Wipe Pattern - An altered bloodstain pattern resulting from an object moving through a preexisting wet bloodstain.