Spoke it over with my technical co-GM. Between my lack of time to actually carry this game on and the fact that everything solvable has been solved, I'm going to be calling this game over. Because the win conditions for each of the non-DM sides were different, it was possible for both sides to win. This is not the case, however.
Now, similarly to Kinjo's game, this was kind of an experiment. (although I forgot to mention this at the beginning). It looks like this sort of game has potential, but will require more fine tuning in the future. (and I do hope to have another game in a similar fashion)
Satoshi was the murderer. He was still in a coma when Ozaki saw him during his morning rounds, but awoke shortly after the arrival of his friends. Keichi's knowledge near the end of the game is a combination of information given to him by Satoshi and what he was actually able to infer. Satoshi's knowledge is related to why he was in a coma. For finding out too much, he ended up being poisoned into a coma that should have persisted indefinitely.
Satoshi took advantage of the volcano eruption and the sensors outside to give the impression that the outside was filled with poisonous volcanic gas, and used that to create the seeming closed room of Ooishi's death (which as solved earlier was a lethal injection of KCl).
Satoshi also was the danger Ozaki faced upon running outside. Satoshi, who was afraid that one or more of the staff would be able to figure out the trick with the gas, laid in wait outside the clinic's main entrance. After all, he had to stop the research being done in the clinic to prevent the spread of Hinamizawa syndrome.
Regarding what happened in the basement, well. Ozaki's board can tell the tale.
And the detective's board
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