Final answer:
In forensic science, evidence is considered no longer needed when it is legal for the owners to own the physical evidence.
Step-by-step explanation:
In forensic science, the evidence is considered no longer needed when it is legal for the owners to own the physical evidence. The ownership of the evidence determines whether it is still required or not. Once the owners have the legal right to possess the evidence, it can be considered no longer needed for forensic purposes.