How criminal’s fingerprints are detected.

Have you ever wondered how detectives find fingerprints from any surface including where no marks are left? You might have heard that a white powder is normally used. Well, that’s right, a white chemical called ninhydrin is used to this effect. The chemistry behind this is quite easy, the ninhydrin which is an organic chemical under a group called Hydrides reacts with amino acids on the surface to form a purple compound. The amino acids come from the sweat on a criminal’s finger which are left on the surface during the robbery. The purple compound forms only along the finger linings hence making a perfect image of the criminal’s fingerprints. This is then scanned and later on compared with other fingerprints in a national biometrics database and whoever the fingerprints will match is the suspect. Ninhydrin is in the same group with formalin which is used in preserving the dead.


Did you know ?

You can see ultraviolet light, the ability is just filtered out by the eye’s lens. Some people have undergone surgery to remove the lense and can detect ultraviolet light.

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