Darla Carmichael, age 14, of Tulsa, Oklahoma, for her question:

When was fingerprint evidence first used against people?

The use of fingerprint evidence against criminals is only a part of the story. When it began, there was no intent to use it against people at all. Way back in history, potters, artists and perhaps kings used a thumbprint as an indisputable signature. In time, the idea developed into a scientific system, organized to benefit individuals and the whole of society. Its main purpose is identification    and it catches crooks only as a sideline.

As we know, the patterns of every person's fingerprints are unique. This was discovered by unknown, sharp eyed observers thousands of years ago. The ingenious Chinese were using thumb and finger prints as indisputable signatures as far back as 200 B.C. Archeologists have found much older fingerprints on clay tablets that may or may not have been used to identify criminals in ancient Babylon.

In India, during the British rule of the 1800s, the old signature idea took two spurts forward. In the 1850s, Sir William Herschel extended its usefulness. He filed the thumbprints of illiterate workers in place of written signatures. The purpose was to record their earnings and make sure that nobody got cheated. The system worked to everybody's advantage and against no one. Its success attracted considerable attention, and attempts were made to improve it.

Around 1890, E.R. Henry was in charge of the Bengal police. The improved fingerprinting system caught his eye, and he saw how it could be used in his work to identify criminals. Henry later became Commissioner of Scotland Yard in London. There he stressed the criminal catching qualities of fingerprinting and founded the basic system now used in most civilized countries.

This aspect of fingerprinting goes back less than a century. When we stress its use as evidence against people, let's remember that the word "against" must have two opposite sides. In criminal cases, there is no doubt what those opposite sides are. One is a person accused of doing something against the welfare of society    society being you and the rest of us ordinary folk.

The accused gets his day in court, and a jury panel of brdinary folk get a to judge his guilt or innocence. And they are not likely to let fingerprint evidence outweigh their evaluation of the total picture. No fingerprint is likely to convict an innocent person.

However, if a criminal's prints on a poker superimpose those left by somebody else, the innocent party is mighty grateful that such scientific evidence exists. Victims of accidents and amnesia also have cause for gratitude for our fingerprint system    and so have their families.