not from the listed four
Regarding the hero, you have evidence linking him to Ilanna. But he couldn't be Ilanna, because he was blocked on the first night.
They started suspecting me because I was solving the interrogation questions, what a nightmare :)
How did Kostyak and Gekasan end up in the four?
Well, if you really want to, you can block/isolate/rob all of us, you have enough actions for that)
Added after 59 seconds
If, of course, you are all peaceful, otherwise you won't have enough blockers, naturally)