Hitman: Absolution HD (EP)

This cannot be done in the prologue (Mission 1: Personal Contract). Any other mission is fine. There is usually a challenge base don making a death look like an accident. You can get this in Mission 2: The King of Chinatown pretty easily. You have different ways to poison the enemy that will unlock the achievement. You can also disguise yourself as a chef near the back of the area. The target will eventually show up and eat some food. You should notice an opening in the ground, and the target notices this as well. He looks down it and you can push him to give him a closer look. This is one of the earliest spots to get the achievement but not the only one. There are several. You may just reload your checkpoint if you want to play the level a different way. Please see the "Silent Assassin" achievement for a video where you don't get caught.