Great game! Love the mechanic, the story is compelling. Simple to play, difficult to progress and intriguing enough to make you want to finish.
My biggest gripe is the way evidence is grouped. The "anchor" piece (the piece of the main thread) that the next group needs to connect to seemed arbitrary for a few groups, which pieces constituted a group seemed arbitrary, and the current group not completing if it was connected to any pieces from upcoming groups (or the wrong anchor) was frustrating. Sometimes, two pieces of evidence would be more related to each other than they were to the rest of the evidence in their respective groups. Overall, this gave it an unnatural feel, like the protagonist suffered rapid-onset amnesia if she saw something of interest but didn't already have a crystal clear picture of how pieces connected back to the beginning post-it.
I understand this system is to enable a linear plot progression, and to allow the player to connect pieces within a group any which way without letting them just connect every piece on the board and have every plot-point trigger at once. I don't think a linear progression is necessary nor fits with the "cognitive map" style gameplay that evidence boards inherently are, not sure what could be done about the latter problem. Perhaps every single piece of evidence should have others it is required to connect directly to, and not worry so much about being able to bundle it into arbitrarily connected groups.