On Gunpoint, I was wondering how to get all the achievements, then I stumbled upon "Clean Record" or something like that, and the achievement isn't clear on what you need to do to get it.
I found this in a Steam Community Guide:
Clean Record: "Complete the police chief’s missions without incriminating yourself."
Don't get caught on any cameras during Mayfield: The Room, then be sure to give him the real file as it's a fake he uploaded to try and catch you lying.
You might have a look at this video too.