When you get to the first body in the bathroom, and are investigating the clues, you need to choose the correct answer to all clues without making mistakes.
- The extinguisher accidentally rolled here after being hit by the bullet.
- The gun belongs to the victim, he tried to defend himself with it.
- The victim injured his face during the fall.
- The victim was killed right on the site.
- The victim fell and hit his head on the washbasin.
Note that there is another achievements to get all clues wrong:
You can exit and reload your save after picking the right answers. You will start just after the elevator balcony.