BLOOD SPLATTER
BLOOD SPLATTER
Blood Splatter is one of the forensic evidences. Bloodstains can occur on a variety of surfaces. The type of surface that free falling blood strikes affects the appearance of the resulting splatter. Bloodstains Analysis is the examination of the shapes, locations, and distribution of patterns of
bloodstains, in order to provide an interpretation of the
physical events that gave rise to their origin.
The following information can be obtained from a Blood Splatter:
1. Distance from the blood source to the target.
2. Direction of travel and impact angles.
3. The magnitude of the force used to cause the bloodshed.
4. The object used to cause the bloodshed.
5. Reconstructed the main events to discover the crime scene.
Blood Splatter Characteristics:
1. Blood will not break up unless it is acted upon by force. The force must be great enough to overcome the surface tension of the blood.
2. Blood forms a spherical shape (perfect circular shape) . The spherical shape is caused by the surface tension of the blood.
3. Surface tension causes the blood drop to pull itself in both horizontally and vertically.
4. The surface tension will maintain the sphere shape of the blood drop until it impacts with the surface.
The following information can be obtained from a Blood Splatter:
1. Distance from the blood source to the target.
2. Direction of travel and impact angles.
3. The magnitude of the force used to cause the bloodshed.
4. The object used to cause the bloodshed.
5. Reconstructed the main events to discover the crime scene.
Blood Splatter Characteristics:
1. Blood will not break up unless it is acted upon by force. The force must be great enough to overcome the surface tension of the blood.
2. Blood forms a spherical shape (perfect circular shape) . The spherical shape is caused by the surface tension of the blood.
3. Surface tension causes the blood drop to pull itself in both horizontally and vertically.
4. The surface tension will maintain the sphere shape of the blood drop until it impacts with the surface.
BLOODSTAIN ANALYSIS EXPERIMENTS
Experiment: The effect of the impact surface on the diameter and shape of bloodstains.
Aim: To test the effect of the impact surface on the diameter and shape of bloodstains.
Hypothesis: The rougher the impact surface, the edgier the drop of blood will be.
Independent Variable: The impact surface of the materials.
Dependent Variable: The diameter and shape of the blood splatters.
Controlled Variable: The height of releasing the blood and the amount blood to drop.
Materials: Blood, different surfaces (film, tile, paper, wooden and lino) and pipette.
Methods:
1. Drop a drop of blood from a pipette at the same height down to different surfaces (in this experiment is 60 centimetres high from the surface of different materials).
2. Observe the diameter of the blood splatters on different surfaces.
3. Take a picture of the blood splatters.
Experiment: The effect of the impact surface on the diameter and shape of bloodstains.
Aim: To test the effect of the impact surface on the diameter and shape of bloodstains.
Hypothesis: The rougher the impact surface, the edgier the drop of blood will be.
Independent Variable: The impact surface of the materials.
Dependent Variable: The diameter and shape of the blood splatters.
Controlled Variable: The height of releasing the blood and the amount blood to drop.
Materials: Blood, different surfaces (film, tile, paper, wooden and lino) and pipette.
Methods:
1. Drop a drop of blood from a pipette at the same height down to different surfaces (in this experiment is 60 centimetres high from the surface of different materials).
2. Observe the diameter of the blood splatters on different surfaces.
3. Take a picture of the blood splatters.
Results:
- Lino (the roughest surface in this experiment):
- Lino (the roughest surface in this experiment):
- Wooden surface:
- Paper:
- Film:
- Tile (the smoothest surface in this experiment):
Analysis:
- Blood drops on a smooth surface (like paper, film and tile) will make a more uniform or regular circular shape.
- Blood drops on a rough surface (like wooden surface and lino) will make an irregular shaped stain with rough or jagged edges.
Errors:
- The amount of blood to drop at every time is different (some of the blood drops are thick but some of them are light => may be it happened due to the blood liquid => we need to shake the liquid well to ensure all of the blood drops have the same thickness).
- The height to drop blood is not the same (may be missed 1 or 2 centimetres).
Conclusion: Even though there were some errors that have slightly affected the results, the experiment was deemed a succeed. The results are similar with the Hypothesis: The impact surface affects the diameter and shape of bloodstains.