Murders & Mistresses: Achievement: You Sure About This One?
Short answer
Suggested fix (unconfirmed): Set Damien to kill Frank out of hatred and Olivia out of jealousy, then visit his store to confront him. Deduce that Damien is lying, Olivia was killed in a fit of passion by strangulation, and Frank secretly watched their sex video.
The problem
Did anyone got this? How to get it? This is my only achievement missing from the Demo :(
Suggested fix (unconfirmed): Start a new game to change the scenario, as the achievement may require a different playthrough. Keep trying across multiple attempts until it triggers.