When is it appropriate for a laboratory examiner to open an evidence bag?

A laboratory examiner should open an evidence bag in a controlled setting for examination. This process is essential to maintain the integrity and chain of custody of the evidence. By opening the bag in a controlled environment, the examiner can ensure that the examination is conducted properly, reducing the risk of contamination or loss of evidence.

In a controlled setting, the examiner is typically under protocols and guidelines that dictate how to handle evidence, document findings, and maintain the integrity of the sample. This controlled approach allows for a complete and thorough examination, which is crucial for accurate forensic analysis and reliable results that can be used in legal proceedings.

The other scenarios, such as opening evidence during a trial, may not provide the necessary conditions for proper examination and could compromise the evidence handling protocols. Similarly, opening evidence only when instructed by a judge could lead to delays or procedural issues, while opening it before the collection process starts does not adhere to established protocols and risks tainting the evidence.