What type of witness statement preserves the legal integrity in a pollution investigation?

A written statement read to a witness with a third-party signature is significant in maintaining legal integrity during a pollution investigation because it creates a formalized record of the witness's account. This type of documentation is often considered more credible in legal contexts, as it includes a verification process wherein the statement is read and agreed upon by the witness, ensuring that the testimony accurately reflects their knowledge of the events in question. The presence of a third-party signature further enhances this integrity, as it provides an additional layer of validation, helping to confirm that the statement was given freely and accurately, thus making it more admissible in court.

In contrast, oral testimony may lack the permanence and verifiability of written statements, while unsolicited oral statements might not be structured or prepared, leading to inconsistency. A signed statement without witnesses may not carry the same level of credibility or verification, making it potentially less reliable in a legal investigation. Thus, the formal process encapsulated in the correct choice helps to uphold the legal standards required in pollution investigations.