Bloodstain Patterns that May be Found. Bloodstains range in both amount of blood and type of pattern—from pools of blood around a body to obvious spatter patterns on the walls to microscopic drops on a suspect's clothing. Left: large volume blood stain. Right: impact spatter pattern. Bloodstain Pattern Analysis (BPA), one of several specialties in the field of forensic science, involves the study and analysis of bloodstains at a known or suspected violent crime scene with the goal of helping investigators draw conclusions about the nature, timing and other details of the crime.‎History · ‎Blood · ‎Blood spatter flight · ‎Area of origin. I realize this trial was a while ago, and technical crime scene methods were less advanced, but blood-spatter analysis is **still** used and held.


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Kirk showed the position of the assailant and the victim, and his research revealed that the attacker struck the victim with his left hand.

Significantly, Sheppard was right-handed [source: The field saw vast expansion and modernization through the work of innovative forensic scientist Herbert MacDonell, who published "Flight Characteristics of Human Blood and Stain Patterns" in Smaller satellite stains may also break away from the initial drop.

By measuring the width and length of the stain, the angle of impact can be calculated, helping investigators determine the actions that may have taken place blood spatter evidence the scene.

Blood Spatter Will Tell

As the angle of impact changes, so does the appearance of the blood spatter evidence stain. As the angle of impact decreases, the spatter stain elongates, becoming more elliptical, and the spines, etc.


Void Patterns A void blood spatter evidence when a person or object blocks the path of the blood. They are important because voids can show investigators if objects are missing from the scene, where a person or persons were at the time of the incident, and if a body was moved.

Blood spatter forensics is bullshit : TheStaircase

An object that leaves a void in a bloodstain pattern will have a matching bloodstain pattern on its surface, allowing analysts to replace it in the scene if found. The point of convergence is the intersection of two bloodstain paths, where the stains come from opposite sides of the impact pattern.

Instead of using blood spatter evidence top-down view, they used a front view.

  • History of Blood Spatter Analysis | HowStuffWorks
  • The Trigonometry of Blood
  • How an Unproven Forensic Science Spread Through the Criminal Justice System
  • How Bloodstain Pattern Analysis Works
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  • Bloodstain Pattern Analysis

The area of origin includes the area of blood spatter evidence with a third dimension in the z direction. Since the z-axis is perpendicular to the floor, the area of origin has three dimensions and is a volume The term point of origin has also been blood spatter evidence to mean the same thing.

However, it has been argued, there are problems associated to this term.


First, a blood source is not a point source. To produce a point source the mechanism would have to be fixed in three-dimensional space and have an aperture where only a single blood droplet is released at a time, with enough energy to create a pattern. This does not seem likely. Second, bodies blood spatter evidence dynamic.

Bloodstain pattern analysis

Aside from the victim physically moving, skin is elastic and bones break. Once a force is applied to the body there will be an equal and opposite reaction to the force applied by the aggressor Newton's third law of motion.

When all the strings begin to intersect, the general vicinity of the attack has been blood spatter evidence. How can his claim be tested?

Bloodstain Pattern Analysis: Principles

Blood blood spatter evidence analysis can help answer questions like this: Was it three feet or six feet from the floor, and how far from the wall? If the blows were delivered closer to the ground—say, around a bed or somewhere a victim was seated—it might be harder for the defendant to argue self-defense.


This method of blood spatter analysis involves extensive photographing of the crime scene, then enlarging the photos to take measurements. Also, blood evidence contamination can occur when criminalists work directly blood spatter evidence their hands, which is why Johnson and his team have blood spatter evidence creating a more sophisticated and efficient blood spatter analysis system.

Along with David Raymond, who specializes in forensic biomechanics and experimental mechanics, and senior engineering students Angela Wu, Jose Rodriguez, Joel Negrete, and Kevin Tepas, Johnson and his team are seeking to revolutionize how blood spatter evidence is analyzed in the field.

Johnson and his engineering team are seeking to identify a better math model that will take all those variables into consideration.

Bloodstain Pattern Analysis: How It’s Done

To help reconstruct events that caused bloodshed, analysts use the direction and angle of the spatter to establish the areas of convergence the starting point of the bloodshed and origin the estimation of where the victim and suspect were in relation to each other when bloodshed occurred.

To find the area of convergence, investigators typically use string to create straight lines through the long axis of individual drops, following the angle of impact blood spatter evidence a flat plane, for instance the floor or wall where the drops are found.

Following the lines to where they intersect shows investigators where the victim was located when the drops were created. To find the area of origin, investigators use a similar method but also include blood spatter evidence height calculations.