tl;dr: I tried to add some criminal psychology into the game. Basically, motives map to modus operandi (how the victim was killed). Figuring them out can help you eliminate some suspects. Interrogations help you figure out motives, but not everyone might be honest or have full information. So, you'll need evidence to figure out who's telling the truth. Admittedly, this part isn't as fleshed out as I would like given the jam's time limit. It's definitely something I'll look into.
Got it, haha.
I think I wasn't clear in my instructions. I'll give an overview first since it helps understand the purpose of interrogations.
Basically, you can crack any case by elimination with evidence found at the location where the suspect died, their motives, which map to their modus operandi (e.g. how was the victim stabbed?), and their abilities (e.g. do they know the area well enough to hide from the cameras?). The algorithm is designed such that there is only one suspect who fits into all this, and this is the culprit.
Interrogations help figure out motives. I was trying to create a type of interrogation similar to one of my favourite games, Interrogation: You will be deceived, which is basically a game about deduction and deception. It's an interrogation game where suspects are almost never honest at first. You have to talk to different suspects, check their claims against each others', and choose the right questions and the right way to ask them to figure out what's the truth.
In L. C. Noire, suspects may lie or simply do not have the full information. For example, for Brigitte's case, people who don't know her well may assume things about her relationship. However, people who know both the victim and Brigitte may read something else in the situation. Then there is the self-proclaimed eye-witness who saw an argument about blackmailing.
Any of them may be speaking the truth or trying to hide their identity as the culprit by pointing finger. The best way to figure this out is to collect evidence at the suspected suspect (Brigitte)'s home.
I think you found a list of lab materials with a meeting time and location? This seems like an illegal trade of lab material or a blackmail message. This makes the last claim (the one about the argument) the most likely.
Since this directly has to do with financial gain and loss, Brigitte most likely has a lucre motive. So, you can exclude her if the victim's body has postmortem stab wounds or been tied up and stabbed, because these indicate strong emotions while lucre-driven modus operandi is more practical. You can also exclude her if the victim died by rat poison since it contains strychnine, which causes intense suffering (as detailed by the Glossary). Brigitte works in drug development research so has access to drugs that don't cause as much unnecessary suffering.
Admittedly, I didn't have the time to flesh out the interrogation part. I could have added more questions that allow you to directly question the suspects about evidence found or hints. It's definitely something I'll look into in future updates.
Though I tried to make the task easier in my game by allowing players to choose the most likely motive once they've read all key conversations related to a suspect. (So all 3 conversations about Brigitte.) I'm not sure if you've been to this part? I admit that the instructions could have been clearer on this.
There is no penalty for a wrong guess, so you can basically try every answer. More details are provided once you make the right choice.
Ok, that was a long post haha. I hope this answers your questions.
Feel free to ask me if you have any questions! Also, if there is a case you're stuck on, feel free to post a screenshot of the report and let me know the evidence found here. I'll do my best to help out!