I would compare the issue to a convenient store robbery where the cashier is caught off guard in the restroom, doesn’t see the perpetrator, and a customer ID’s the robber as he is exiting the store.
As the police arrives, the customer tries to get the cop’s attention to describe the robber...
But the cop ignores the witness because he doesn’t run the store... and when the witness insists that he saw the robber, the police merely suggests that his testimony is worth nothing in court.
hehehe, i figured the cop would haul away the witness and the clerk would just shrug and say thanks for solving the case...