The story continues as your junior CSI's delve deeper into the evidence found at the classroom crime scene.
As usual, the fascinating Mrs. Johnson, a science teacher at Crooked Creek Middle, began her lesson with a story. Because the students had been trying to solve the mystery of who had broken Mrs. Johnson’s cookie jar, they knew her story would be another step toward understanding crime-solving techniques. All of the students leaned forward in their seats and gave Mrs. Johnson their full attention.
“In 1888, all of Europe was gripped by the grisly murders committed by a mysterious man named Jack the Ripper. Investigators from Scotland Yard (the headquarters of British detectives) did their best to apprehend the criminal, but the terrible killer was never identified.
At the turn of the century, the interest in solving crimes continued, and the flames of this interest were fanned by the ever increasing popularity of a series of stories about Sherlock Holmes, a fictional detective who used his keen powers of observation to solve mysteries.
But all investigative techniques were quite simple until about 1910, when a Frenchman named Edmond Locard approached the Lyons, France, police department and set up one of the world’s first forensic laboratories. Locard had an important theory.”
Mrs. Johnson stopped for a moment and called on George, who had raised his hand.
“We’re going to talk about Locard’s Principle, aren’t we, Mrs. Johnson.” It was more of a statement than a question.
Mrs. Johnson was impressed. “You seem to have done your homework, George.”
George flushed with genuine embarrassment, but he continued, “I guess you could say I’ve been investigating!”
“What can you tell us about Monsieur Locard, George?”
“Well, let me demonstrate.” George stood up, and as he did so, he nudged Jennifer, who was seated in front of him, and indicated that Jennifer should stand up. She did. “Locard believed that people who are in contact with each other—even casually—“(and here George shook hands with Jennifer quickly) “exchange something, some kind of evidence. It’s usually something we don’t even see, like skin cells, fibers, hair, or even germs. If I just brush past Jennifer, I might pick up some fibers from her sweater.”
“And I might exchange some hairs from you!” said Jennifer to George. She sat back down in her seat, and so did George.
“Exactement! Exactly!” laughed Mrs. Johnson. “Excuse my French!”
“So that’s Locard’s Principle, Mrs. J.?” asked Mark. “What does that have to do with our mystery? I don’t think two people were involved in breaking your cookie jar!”
“Maybe not, Mark. But Locard’s Principle isn’t only about people running into each other, it’s also about the contact between people and things.”
“So, you mean, whoever broke the cookie jar must have left something behind?” asked Jennifer.
“Some evidence was collected,” Mrs. Johnson continued. “I put it in an envelope marked ‘crime scene fiber.’ Let’s try an experiment and see what we can learn from applying Locard’s Principle!”
Continue the story in the next module, First Impressions, here!
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