The Murder of Sister Margaret Ann Pahl

Before the satanic panic of the mid-80s and the accusations of the sexual abuse within the institution, the Catholic Church managed to cover up a murder in Toledo, Ohio. It shouldn't come as a surprise because they were a very powerful organization back in the day and would do anything to save their reputation, including manipulation. The murder victim was a nun, and the only suspect - a priest. Knowing how the public would react if this got out to the media, the higher-ups from the Catholic Church stopped the investigation completely, removing the accused from the area.
However, it took a single letter from 2003 for this case to be re-examined in a new light. And after more than two decades later, the justice was finally served.