I really like the ideas behind this game and its potential. The whole corkboard murder board provides a great tactile feel to things. I understand the concept of what's going on and kind of what I need to do, but it was pretty hard to map out, especially with having to remember all the controls. Having a graphic somewhere of the two examples with the same mail item and what the board would look like in the keep and trash scenarios would have been really helpful. It could be worth editing your game page with updated instructions and this type of example. I also didn't understand the circle asking about the cop piece of things at all, I was expecting some extra information to pop-up about that conversation at the end of the week or something.
Definitely doing a pass on streamlining the interaction mechanics would be helpful post-jam. Like having to click again on the board and fiddle with tab to select suspects was cumbersome. It'd be great to just have clicking be the primary interaction, then have buttons to keep or trash mail, and when you add a new note to the board have it be a choice menu of the suspect you want to add, avoid the whole having to interact with the note. Having a manual advance to next week after the mail has been sorted would be helpful too, as if you don't just put the mail down again after and make a note, then you have to wait a few seconds and have to keep that info in your mind.
Also, what prevents you from just trashing all the mail? It could be handy to have something like 'suspicion' where if everyone hasn't gotten a piece of mail by the end then that's a losing scenario too.