Swipe/Wipe

Swipe and Wipe are terms used when blood is put onto a surface, wipe’s occur when something that is not blood stained move through a bloody surface. Swipe’s occur when a bloody object moves across a non-bloody object.

Transfer Patterns

Transfer patterns occur when something bloody is placed on a surface and some form or recognizable shape is produced.

Blood into Blood,

When blood drops fall into a blood drop that already hit a surface, the blood makes a satellite kind of shape. Other drops are usually made from that drop as well.

Expiratory blood,

Expiratory blood is blood is blood that come out of an air way or passage way as result of a cough or sneeze.

Arterial Spurts happens when a victim’s artery is breached or punctured. Because the human heart is a very strong pump the blood is going to be pushed out at a significant
amount of speed, that blood deposition it creates is a rather distinctive blood spatter when
it hits a vertical surface.

Cast off stains happen when an object with blood on it, is moving at a significant amount of speed and that blood hits a surface. Usually the blood is in a vertical line.

For the next three days I’ll be discussing 6 different Blood Spatter topics including,

Blood into blood

Expiratory blood

Point of origin

Shadowing/Ghosting

Swipe/Wipe

Transfer Pattern

The inward spiral search: The CSI starts at the perimeter of the scene and works toward the center. Spiral patterns are a good method to use when there is only one CSI at the scene.

The outward spiral search: The CSI starts at the center of scene (or at the body) and works outward.

The parallel search: All of the members of the CSI team form a line. They walk in a straight line, at the same speed, from one end of crime scene to the other.

The grid search: A grid search is simply two parallel searches, offset by 90 degrees, performed one after the other.

The zone search: In a zone search, the CSI in charge divides the crime scene into sectors, and each team member takes one sector. Team members may then switch sectors and search again to ensure complete coverage.

Ninhydrin

Ninhydrin (triketohhydrinedene hydrate) is a staple of law enforcement investigators and has been used for years to reveal latent prints. The object with the supposed latent print is dipped in or sprayed with a ninhydrin solution. Because the reaction between the ninhydrin and the oils of the print is extremely slow, the latent print may take several hours to appear as a purple-blue print Heating the object to a temperature of 80 - 100 degree’s fahrenheit speeds up this process.

Silver Nitrate

Silver nitrate is a component of black and white photographic film. When investigators expose a latent print to silver nitrate, the chloride in salt (sodium chloride) molecules present in the print residue reacts with the silver nitrate and forms silver chloride. This colorless compound develops, or becomes visible, when it’s exposed to ultraviolet light, revealing a black or reddish-brown print.

- Brandon Anderson

Tags: forensics, chemistry, ninhydrin, silver, nitrate