Introduction to Super Sleuths
Crime is as old as time.
As soon as man formed societies and lived together, crimes were committed. And when the societies set up organizations to catch and punish them, criminals tried to avoid capture. Two hundred years ago, this was as simple as making sure that no one saw you commit the crime. Today, however, even the most-clever criminals leave behind some trace of their presence at the scene of the crime, and scientists can help the police to identify them.
Scientists who specialize in examining evidence and helping to solve crimes are called Forensic Scientists. The word forensic refers to the Latin word forensis, meaning legal. The goal of forensic science is to provide enough convincing evidence from a crime scene to the legal authorities so that a suspect can be successfully prosecuted.
Archimedes was probably the first forensic scientist. One legend says that a King had ordered a special gold crown from a local goldsmith but suspected that it might not be pure gold. He asked Archimedes to determine if he had been cheated, but he did not want the crown to be damaged by any tests. One day, while bathing, Archimedes noticed that the water level in the tub went up when he got in because his body had displaced its volume in the water in the tub. He realized that he could add gold to a container of water until it displaced the same volume as the crown. If the crown was pure gold, it would weigh the same as the gold Archimedes used for the experiment. The legend also says that when the idea came to him, he leapt from the tub and ran through the streets shouting, "Eureka, .eureka", which means "I've got it, I've got it". He determined that the crown was not pure gold. When confronted with the evidence, the goldsmith admitted that he had mixed silver in with the gold. Case closed.
As early as 1248, Chinese doctors suggested that medical evidence could be used to determine the cause and manner of death. Even during the Salem Witch Trials, doctors were called as expert witnesses to explain the "evidence". As progress was made in science, and in methods of identification, law officials began to rely more on science. It's various branches have made many contributions to crime detection. Members of the forensic investigation team include chemists, dentists, biologists, pathologists, who analyze body fluids and tissues, toxicologists, who specialize in finding and examining drugs and poisonous substances in body tissues and fluids, serologists, who study body fluids, technologists, who specialize in operating the high tech instruments use to analyze evidence, and of course, the police.
One of the early pioneers in establishing forensic science as a part of the justice system was Edmund Locard of France. He established the world's first crime lab in Paris in 1910. (NOTE: The first American crime lab was opened in Los Angeles in 1923).
Locard is famous for his "Principle of Interchange". In 1910, he was the first to theorize that when someone commits a crime, that person always leaves something behind that was not there before and/or carries away something that was not on the person when he or she arrived. This is one of the basic principles of criminal investigation. Locard's Principle applies to fingerprints, bloodstains, footprints, and also to traces of evidence such as hair, fibers, wood chips, glass fragments, or paint flakes.
Today, using sophisticated instruments, forensic scientists can identify what kind of car a paint flake or carpet fiber came from, whether or not someone fired a gun recently, if a document was forged, if someone was poisoned, or if a fire was caused by arson. In each case, scientists have developed a method for detection and identification.
In this set of experiments, you will be the forensic scientist and use scientific methods and Locard's Principle to help solve crimes.