Solving a crime by looking at the splatter isn't an easy job. Sometime it's even harder to look for evidence of blood splatter. The blood stains can fade away and be wiped away by the criminal which leaves no trace left for the investigators to work on. That's what the criminal thinks.
Scientists have a number of ways to identify blood stains even if they've faded away due to several reasons.
Scientists use a type of spray which reacts with the iron in blood to identify blood stains. Let's look at an example.
Scientists have a number of ways to identify blood stains even if they've faded away due to several reasons.
Scientists use a type of spray which reacts with the iron in blood to identify blood stains. Let's look at an example.
A blood stain created by a person walking in a crime scene with blood stick to his shoe sole. This is a fairly visible blood stain.
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How about this one? It's not easy to detect at all.
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![Picture](/uploads/5/9/5/6/59567625/7654207_orig.png)
After using the spray, the footprint of the person is revealed.
![Picture](/uploads/5/9/5/6/59567625/1681164_orig.jpg)
Another to detect whether blood trace is by spraying Luminol solution in a darken room. The area where blood was present but then wiped away would glow blue. The more a person wanted to wipe or conceal away, the (bluer) that place would be.
![Picture](/uploads/5/9/5/6/59567625/9647837_orig.jpg)
Examination of blood splatters at a crime scene is necessary and the results from blood splatter is extremely valuable.
A crime investigator can reconstruct the crime just by looking at blood stains at a crime scene. The method of fitting together bits and pieces of how the crime happened is called "stringing".
A crime investigator can reconstruct the crime just by looking at blood stains at a crime scene. The method of fitting together bits and pieces of how the crime happened is called "stringing".
Beside enabling the investigators to reconstruct the crime, other factors can be determined as well when looking as blood splatters:
- Height of dropping
- Angle of dropping
- Impact surface
When blood is dropped vertically (at 90 degrees), onto a stationary, flat surface, the result is a circular mark.
- Height of dropping
- Angle of dropping
- Impact surface
When blood is dropped vertically (at 90 degrees), onto a stationary, flat surface, the result is a circular mark.
The height of falling for a drop of blood can affect the shape of a blood drop. The higher the blood was dropped, the more serrated and the bigger the blood drop appears to be. When blood is dropped at 6 inch form the impact surface, the blood splatter looks circular and relatively smaller. This is different when blood is dropped at 7 feet from the impact surface, the stain becomes bigger and there are some tiny spatter around the drop.
![Picture](/uploads/5/9/5/6/59567625/2404272.png?773)
When blood is dropped from an angle, the blood drop is elongated. The smaller the angle of impact is, the smaller the diameter of the blood is. As when the angle of impact is 10 degrees, the blood drop appears to be a long drop with the diameter of 1 cm. When the angle of impact is 90 degrees, the blood drop appears to be around, with no tails or bolder stains. The tail shows the direction of movement.
Different impact surfaces have different effect on the shape of the blood stains. See a detailed experiment on effects of impact surfaces on blood stains here.
By looking at the blood stains, the investigators can also determine whether the criminal walked away from the crime scene or ran away. The criminal who leaves the crime scene walking will leave behind circular drops of blood. Unlike that, a criminal who ran away will leave behind blood drops with spiny edges. |