Trace evidence consists of small items of material largely made up of human and animal hair, cloth fibers (natural and synthetic), items such as geological soil, small glass particles, pollen, wood splinters, gunshot residue, and small smears or flecks of paint. These items are found throughout many crime scenes and are often overlooked or lost.
Explain to your CSI partner in training the methods of finding trace evidence, cautions on not losing or destroying it, and collection methods.
Relate to your partner the components of human hair that are considered class characteristics.
Further, explain how the Locard Principle plays a major part in the transfer of trace evidence and the importance of identifying and collecting it for the investigation.
Full Answer Section
Here are some of the components of human hair that are considered class characteristics:
- Color: The color of human hair is determined by the amount of melanin it contains. There are many different shades of human hair, so color is a good way to distinguish between different people.
- Texture: The texture of human hair is determined by the shape of the hair shaft. There are three main types of hair texture: straight, wavy, and curly.
- Coil pattern: The coil pattern of human hair is determined by the way the hair shaft twists. There are three main types of coil patterns: spiral, elliptical, and irregular.
The Locard Principle states that "every contact leaves a trace." This means that when two objects come into contact with each other, they will exchange trace evidence. This trace evidence can be used to link the two objects together.
The Locard Principle is important for trace evidence investigations because it means that even if the perpetrator of a crime tries to clean up the scene, there is still a chance that they will leave behind trace evidence. This trace evidence can be used to identify the perpetrator and help solve the crime.
Here are some additional tips for finding, collecting, and preserving trace evidence:
- Use a magnifying glass or other light source to help you see trace evidence.
- Take photographs of the crime scene before you start collecting evidence. This will help you document the location of the evidence and its condition.
- Use clean, disposable gloves when collecting evidence. This will help prevent you from contaminating the evidence.
- Place the evidence in a clean, sealed container. This will help preserve the evidence and prevent it from being damaged.
Sample Answer
Sure, here are some tips on how to find, collect, and preserve trace evidence:
- Look for the small stuff. Trace evidence is often very small, so it's important to be thorough when searching a crime scene. Look for things like hair, fibers, glass, soil, pollen, and paint.
- Be careful not to disturb the evidence. Once you find trace evidence, be careful not to disturb it. This could damage the evidence or make it harder to collect.
- Collect the evidence properly. If you're collecting trace evidence, it's important to do it properly. Use the right tools and techniques to avoid contaminating the evidence.
- Preservation is key. Once you've collected trace evidence, it's important to preserve it properly. This means storing it in a clean, dry environment and keeping it out of the sun.