Works I did in school...

Locard's Principle

The Locard's Principle is when you step into a scene, and you leave with part of you still there, but also take something from the scene. It can be a strand of hair that has fallen, a footprint laid, or fibers from clothing. It can be from anyone at a scene to show evidence such as a broken glass, tools, blood, paint, or anything that's there that might be unusual. If there was paint in a certain area, and you walk there it can be a possibility where u stepped in it, and if you do then it's be on your shoe even if you're some place else.

A real life example that illustrates the Locard's Principle is when you step into a classroom. Once you open the door to the classroom your fingerprints are handled on the door knob. One thing you may take out of a classroom is knowledge or a borrowed pencil. It can also happen simply by resting your head on the table because a strand of your hair might fall out. Another example is drinking from a cup, could leave DNA.

Locard's Principle is applied to modern criminal investigation because you need to be extra careful when going into a scene, so false evidence doesn't accidently fall. That's why it's important to wear gloves, so fingerprints aren't laid. This is also applied because once you enter, and before you leave a crime scene you have to write your information "name" in a security log.