Forensics Unit 2: Bloodstain Pattern Analysis

Bloodstain formation

is the process by which blood droplets and patterns are created upon impact or environmental influences.

Passive bloodstains

Blood patterns that are created by the force of gravity, typically resulting from blood dripping or oozing from a wound.

Transfer Bloodstains

Blood patterns are formed when a bloodied object comes into contact with a surface, resulting in the transfer of blood onto that surface.

Impact Bloodstains

Are patterns created when blood is projected onto a surface due to force or impact, often resulting from gunshots, blunt force trauma, or explosions.

Cast-off Pattern

A bloodstain pattern created when blood is released or thrown from a bloodied object in motion, often resulting from a swinging motion of a weapon.

Arterial Spatter

A bloodstain pattern resulting from a ruptured artery, characterized by spurted blood that is expelled with high pressure, is typically seen in cases of severe injuries or trauma.

Void Spatter

A bloodstain pattern created when an object blocks the path of blood, leaving an area with a lack of blood spatter, indicating the position of the object during the bloodshed.

Direction of blood travel

Often indicated by the narrow end or tail of an elongated stain.

Angle of impact Formula

Arcsin (Width/Length): used to calculate the angle at which a blood droplet strikes a surface, where width is the width of the stain and length is the length of the stain.

Area of convergence

is the 2D area containing the intersections of lines drawn through the long axes of individual bloodstains, where the paths intersect. (Typically measured on flat surface)

Area of origin

is the 3D location from which blood droplets originate, determined by analyzing the angles and points of impact of bloodstains. (Typically measured to find the height from which the blood was projected)

Collection of bloodstains

is the gathering and preservation of blood samples and associated stains from a crime scene for analysis in forensic investigations. This process is crucial for DNA profiling and blood pattern analysis.

Analysis of Bloodstains

involves examining the size, shape, and distribution of bloodstains to draw conclusions about the events that led to their creation. This analysis helps to reconstruct the scene and understand the dynamics of the bloodshed.