See the linked article from the Harvard Business Review:

Harvard Business Review  – Amy Gallo   JUNE 04, 2015

“Sometimes you sense that something isn’t right at work. You suspect that your finance colleague might be fudging numbers, your boss isn’t telling his manager the truth about an important project, or your co-worker is skipping out of the office early but leaving her computer on so it looks like she’s just down the hall. How do you know when it’s worth speaking up or not? Can you you protect yourself from potential consequences of calling out bad behavior? And when you do decide to say something, what do you say and to whom?” Interesting perspective on reporting ethical issues at work.