Pattern Types

Passive

Bloodstains created by only the force of gravity acting on the blood. The following are secondary classifications that are a subset of passive bloodstain patterns:

Single blood drops that are relatively round with almost no satellite spatter, formed due to gravity only.

A pattern formed from a liquid dripping into another drop of liquid, where at least one of the liquids is blood.

A pattern that is formed by blood dripping from a moving object or person onto the ground, outlining the direction of movement.

A bloodstain pattern that forms by gravitational forces causing movement of a small or large volume of blood from an initial droplet

A form of bloodstain that has no characteristic shape but indicates that there was an accumulation of a large volume of blood on a specific substrate. These bloodstains take their shape without any accompanying satellite spatter.

Small drops of blood distributed around the main blood droplet. The number of droplets and their distribution around the spatter depends on the nature of the surface the blood spatter is found on.

A bloodstain that has no characteristic shape but originated from an accumulation of a large volume of blood on a porous substrate (e.g., sheets, pillows, carpet) thus has been absorbed into its matrix. Once the material has absorbed all it is saturated and it can then begin to pool on the surface.

A form of pattern formed by blood falling into other blood. This is usually the situation of larger volumes of blood or blood dripping from higher heights results in more satellite spatters.

Spatter

Bloodstains resulting from a blood drop encountering an external force that will cause it to break apart resulting in dispersion.The following are secondary classifications that are a subset of spatter bloodstain patterns:

This is created when a blood-bearing object is put into motion causing the blood of the object to be released tangentially to the object’s movement and landing on a nearby surface.

A bloodstain pattern made from the expulsion of blood through the mouth, nose, or respiratory system. It can result in mucus or bubbles in the blood spatter.

A bloodstain pattern resulting from an object forcefully impacting a blood source. This results in the blood spraying away from the impact site.

A bloodstain pattern formed by the blood being propelled out of a breached blood vessel, often an artery.

A bloodstain pattern made from a high-velocity bullet impacting a blood source, resulting in a mist-like deposit of fine drops on a surface.

Transfer

Bloodstains resulting from the contact between two surfaces/objects, where one has blood and the other does not. It sometimes can consist of friction ridge patterns. The following are secondary classifications that are a subset of transfer bloodstain patterns:

A type of transfer pattern where a moving blood-bearing object makes contact with a blood-free surface. As the blood-bearing object moves along the surface, it transfers blood onto it, from which the direction of movement can be inferred.

A type of transfer pattern created when a blood-bearing object is brought into contact with a blood-free surface. The blood-bearing object can leave behind a partial or a full imprint that may indicate the direction of movement of the object.

A type of transfer pattern where a moving blood-free object makes contact with a blood-bearing surface. During the motion the blood transfers and spreads out onto the blood-free object, from which the direction of movement can be inferred.