Here's why:
* Paper bindle/envelope: This is crucial because it allows the evidence to breathe and prevents moisture buildup, which can lead to degradation of DNA. Paper is also preferred as plastic can cause static electricity, which can degrade the sample.
* Tamper-evident outer packaging: This ensures the integrity of the evidence and provides a clear indication if the packaging has been opened or tampered with. This could be a sealed envelope, a sealed bag, or a container with security tape.
* Labeling: Clear and accurate labeling is essential. The label should include:
* Case number
* Item number
* Date and time of collection
* Location of collection
* Description of the evidence (e.g., "fingernail scrapings from victim's left hand")
* Collector's initials/signature
* Chain of Custody: Maintaining a proper chain of custody is paramount. This involves documenting everyone who has handled the evidence, from collection to analysis.
Why not other options?
* Plastic bag: Plastic bags are generally avoided for biological evidence because they trap moisture, which can degrade DNA and promote mold growth.
In summary, the ideal packaging protects the evidence from contamination, prevents degradation, and maintains the chain of custody.