In the world of law enforcement and forensic investigation, maintaining the integrity of evidence is everything. A single mistake in evidence handling can compromise an entire case. That’s why using the right plastic evidence bag — and using it correctly — is so critical. These bags are specifically designed to store, seal, and protect evidence collected from crime scenes. However, even experienced personnel can make mistakes that risk contamination or chain-of-custody errors. Here are five common mistakes to avoid when using plastic evidence bags to ensure accuracy, reliability, and security.
1. Choosing the Wrong Type of Evidence Bag
Not all evidence bags are created equal. One of the most common errors is using a standard plastic bag instead of a crime scene bag designed for evidence handling. Plastic grocery or storage bags may look similar but lack essential features such as tamper-evident seals, write-on panels, or tracking barcodes. These specialized bags are manufactured to maintain forensic integrity by preventing moisture, contaminants, and tampering. Always select a plastic evidence bag that matches the specific type of evidence — for example, paper bags for biological materials and plastic ones for non-biological or dry evidence.
2. Failing to Label the Bag Properly
Accurate labeling is a crucial part of maintaining the chain of custody. Every crime scene bag should clearly display essential details such as case number, date, time, collector’s name, and a brief description of the contents. Incomplete or illegible labeling can cause confusion or even render the evidence inadmissible in court. Use a permanent marker or pen suitable for writing on plastic and ensure the information is recorded before the bag is sealed.
3. Mishandling or Contaminating Evidence
One of the main purposes of using a plastic evidence bag is to prevent contamination. However, mishandling during collection or packaging can introduce fingerprints, DNA, or environmental materials that alter the evidence. Investigators should always wear gloves, change them between each item of evidence, and avoid touching the inside of the bag. Additionally, items should be dried thoroughly before sealing to prevent mold growth or degradation.
4. Ignoring Proper Sealing Procedures
Tamper-evident seals are designed to show any unauthorized access to a crime scene bag. A frequent mistake is failing to press or apply the seal correctly, leaving small gaps or loose edges that compromise the security of the contents. Always double-check that the adhesive strip is fully engaged and that the seal number matches the documentation. Once sealed, never reopen the bag unless authorized procedures are followed, and a new bag is used for resealing.
5. Improper Storage and Transportation
Even after evidence is sealed, improper handling during storage or transport can damage it. Avoid exposing plastic evidence bags to extreme temperatures, direct sunlight, or rough handling. Evidence should always be stored in a secure, climate-controlled environment to preserve its condition. When transporting multiple items, each crime scene bag should be placed separately to prevent cross-contamination or accidental damage.
Conclusion
Proper use of plastic evidence bags is fundamental to upholding justice. By avoiding these common mistakes — from incorrect labeling to improper sealing — investigators can maintain a reliable chain of custody and protect the integrity of every case. In law enforcement, even the smallest detail can make the biggest difference, and handling evidence with precision ensures that truth and justice prevail.