After playing for a few hours, there's a few techniques that can be so overwhelmingly effective it can ruin the game.
First is sales ledgers. Once you are aware of the sales ledger for the black market, it's so easy to identify the killer with it that it can even make the very crime scene irrelevant. I have been having a lot of repeated gun murders in my save so this has been incredibly obvious for me. Some options I think would help would be having the killer use a fake name often when purchasing ammunition, or perhaps if they already like guns, maybe they shouldn't purchase ammo at all and simply use ammo they already have. In it's current state, you can simply pin the sales ledger and have it automatically update in your memory and witness a suspect purchase instantly and have a name.
The second issue is fingerprints, and specifically the ease of gathering records on them. Using business photos and employee records in tandem can allow a savvy detective to go from business to business and accumulate fingerprint data on everyone in town rather easily. In addition to not being very fun, it's so effective that the player can 'optimize themselves into having no fun'. I'm of the opinion that business employee records should not have fingerprint data, and that the government database should made harder to use, perhaps by increasing the amount of characters you must type before the system gives you name suggestions, or perhaps only people who have been arrested for something before have had their fingerprints taken and catalogued
