How to use "established" in a sentence

Elliot didn't tell the judge about the malicious prankster, for that seemed like an unnecessary complication; he still believed that once the fact of Danny's death was established by the exhumation, the quickest and surest way of dealing with the harassment was to hire a first-rate firm of private investigators to track down the perpetrator

Even if the government had established a secret police force, however, why was it so anxious to cover up the true facts of Danny's death? What were they trying to hide about the Sierra tragedy? What really had happened up in those mountains?