Sorry, I'm going to interject there. Just because the person is no longer an employee does not mean that the investigation of the existing complaint should not be completed. The finding of the complaint at the time of the issue, and of the case when it happened, should still have an outcome. When a person leaves, that means the disciplinary action that may follow may not be applicable, but it doesn't mean that the complaint is not a valid complaint and not worthy of investigation.
On March 20th, 2018. See this statement in context.