Often, the Whistleblower will not have a personal interest in the concern that they are raising and it will be more about the concern of danger to others or illegality. Therefore, they should not be expected to prove the malpractice, they are simply the messenger raising the concern and the appropriate people should be assessing whether or not the allegations are true.

This is different to a complaint, the complaint is usually based on the person complaining about being treated poorly. The person making the complaint will have a vested interest in the complaint and is expected to be able to prove their case.