Players need to rely on their own observational skills and notebook. Explore crime scenes, gather clues, and question witnesses to try to piece some clues together. The game's developer, Frogwares, recently developed some of the latest Sherlock Holmes titles, so I would expect that part of The Sinking City to be fully realized. In fact, Charles Reed has a unique ability to replay past scenes when trying to solve some of these mysteries, a gameplay element seen in those Sherlock Holmes games.
In order to succeed in their investigation, the player will need to collect clues, figure out what they have in common, and try to back up their theories using one of the game’s essential tools called the Mind Palace. While it will let the player submit their hypotheses about potentially guilty parties, it will never tell them whether they're on the right track. The player will have to accept the consequences of their choices.