How do you determine point of origin?

By measuring the width and length of a single drop of blood, you can determine the angle of impact. By using the Law of Tangents, you can calculate the height from which the blood fell, or the point of origin for the blood.

What does area of origin tell investigators?

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.

How is the area of convergence determined?

Area of Convergence. If you have a number of bloodstains, the area of convergence can be determined by drawing lines from the leading edge of stains through the long axis. The lines come together in a general area where the blood has emerged, helping to locate the origin of the bloodstains.

What is the meaning of point of origin?

the place where something comes from
Definition of point of origin : the place where something comes from : the place where something originates The package’s point of origin was somewhere in the U.S. the point of origin of the fire that burned the building down.

How do you determine the point of origin of a fire?

The side of a tree with the most damage is probably facing the starting point of the blaze. Fires burn blades of grass from the bottom up, so fallen tips of grass that is unburned will point in the direction of the original fire. As fires gain momentum over time, they tend to burn higher.

What information can an investigator gain from the location of the area of origin of a bloodstain pattern?

What information can an investigator gain from the location of the area of origin of a bloodstain pattern? Position of the person form which the pattern originated.

What does the tail of a blood drop tell you?

The “tail” or wave castoff of the bloodstain generally points to the direction of travel of the blood drop. The direction of travel and the angle of impact are referred to as the directionality of a bloodstain pattern. The directionality of a bloodstain will be used for reconstructing where the bloodshed occurred.

What does the Kastle Meyer test for?

The 3-stage Kastle–Meyer (KM) test has been used for decades as a rapid, presumptive test for blood. The test identifies the heme component of hemoglobin, which in the presence of hydrogen peroxide catalyzes the oxidation of the indicator phenolophthalin, turning it pink [1], [2].

What is the difference between point of convergence and point of origin?

Point (Area) of Convergence — The common point (area), on a two dimensional surface, over which the directionality of several blood drops can be retraced. Point (Area) of Origin — The common point (area) in a three dimensional space to which the trajectories of several blood drops can be retraced.

What is an area of origin in blood?

Area of Origin (AO): The three-dimensional location from which spatter originated (SWGSTAIN, 2017). Angle of Impact: The acute angle (alpha), relative to the plane of a target, at which a blood drop strikes the target (SWGSTAIN, 2017). Impact Medium: A surface upon which blood has been deposited.

How does an area of origin differ from an area of convergence?

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.