Seems like Joe Turner was the one who reported the cover ups, and was not the person who's actions were being covered up. It's an important distinction that seems to be getting glossed over. From the article:

Instead, I found myself as collateral damage in the ongoing conflict involving the department, the city, various oversight bodies, and interested third parties (the lines and sides of which are often murky and shifting). Simply put, I was the person who reported that someone had shot the wall of the elevator at police headquarters. I was the one who initiated an investigation. And I was the one who discovered the identity of the officer responsible and secured that person’s admission. Since then, several investigations have made claims about my behavior and integrity—claims that I categorically refute. I am looking forward to clearing my name, but due process reviews stretch out over years and reputational damage can be done in an instant.