It is not necessarily the case that an exposition of a telephonic conversation in audio necessarily mandates an investigation from a moral perspective. Whether an investigation is warranted would depend on the content of the conversation and the context in which it took place. If the conversation reveals misconduct or wrongdoing on the part of the public office holder, then it could be considered a matter of public concern and an investigation may be morally justified.
Khan's audio leaks
— Zorays Khalid (@zorayskhalid) December 20, 2022
However, if the conversation is a purely personal matter and does not involve any wrongdoing, then an investigation may not be justified from a moral perspective. It is important to consider the privacy rights of individuals and to ensure that any investigation is conducted in a fair and transparent manner. My suggestion is to ask him, not accuse him. Should he give a statement too and send a video for forensics?
