SPOILER AHEAD, I RECOMMEND FINISH THE GAME BEFORE YOU READ IT
So I tried the game 4 times and tried all 3 suspects, but each time it turned out to convict the wrong person, not sure what I'm missing here, as far as I can tell the statements are same the each time, and the heartbeat monitor afaik doesn't tell much useful information, I even try to confront the suspects when their heart rate is high, no dice. I'm sure I'm missing something here, maybe a hidden mechanic, which might be the "procedural" part. But I really couldn't figure that out so I'll rated this lower that I think it deserved for now, would love if the you can respond and tell me what I missed out on and I'll retry it and probably change the rating.