In the past 90 years, humble fingerprints have brought countless criminals to justice.

When a criminal or suspect is brought into the police station, the police will ask him to press the fingerprints of each finger on a white paper. Fingerprints have now become the most important basis and evidence for identifying criminals and finding criminals.

The probability that two people have the same fingerprints is so small that it is almost zero. Only in 1000 trillion people can there be two people with exactly the same fingerprints. So we have every reason to say that just as there are no two identical snowflakes, there are no two people with the same fingerprints in the world. Therefore, if the police find a fingerprint left by a criminal at a crime scene, and it matches the fingerprint in a fingerprint file, the criminal's identity can be determined immediately.

Fingerprints have been used to identify and determine people’s identities for a long time. Hundreds of years ago, the Chinese used thumbprints to sign documents or contracts, which may be safer than a signature because it cannot be forged. But the first person to use fingerprints to systematically identify people was Englishman William Herschel around 1850, when he was a British government official in India. Hershel was troubled by the fact that Indians often pretended to be each other's names, so he came up with the idea of ??using fingerprints to identify everyone. His measures worked immediately, and no one could fish in troubled waters and hide their identity anymore.

First, he divided fingerprints into three major categories based on their different shapes - bow-shaped fingerprints, dustpan-shaped fingerprints and bucket-shaped fingerprints. In this way, when verifying a person's fingerprints (to see if he has a criminal record, or to look for the same fingerprint in the file after taking the fingerprints from the crime scene), you only need to check against the same type of fingerprint file, instead of all the fingerprints in the file. Fingerprint records are checked.

When detectives examine a crime scene, they may be lucky enough to find fingerprints that are visible to the naked eye, such as those left on an object stained with blood or oil, so they can simply take a photo of the fingerprint. That's it. But more often than not, fingerprints are concealed or difficult to distinguish. There are two ways to make such fingerprints visible. If the fingerprint is printed on a hard object, such as a wooden or metal object, you can sprinkle some very fine powder on it (the color of the powder must be different from the color of the object), and then lightly brush it with a small soft brush. In this way, the powder left on the object will reveal the fingerprint. If the fingerprint is left on a softer object, such as paper, it will be developed using a compound containing iodine or silver (just as you would develop a printed photograph).

There is a very powerful compound called dihydrocarboxylic acid, which can reveal fingerprints left on items years ago.

Today, police in most countries have detailed fingerprint files of criminals. Perhaps the largest fingerprint archive in the world currently is that of the FBI in the United States, located in Washington. Among them, there are fingerprint records of 200 million people!

Fingerprint identification also has other uses, such as verifying the identity of a person who has lost his memory; identifying the identity of an unknown deceased, etc.

Since the fingerprints of newborn babies are not yet fully developed, in order to ensure that the baby will not be transferred, the hospital adopts the method of collecting foot prints.

You know, foot prints are already complete when a person is born, and like fingerprints, they are also unique!