Two-Face. He flips a coin to determine what he does, that's his thing. And there hasn't been a coin since Circus died.
Night 1, two kills. One of them seems to be Gheb, targeting X1 (Harley). The other was Raj, the Tick. There was a coin, facing tails.
Night 2, one kill. JTB, ??? flip. Coin facing tails. Circus told us at the time that JTB wasn't town.
Night 3, one kill. Gheb, Wolverine. Coin facing tails.
My theory is that it controlled their factional night kill. The image was at the start of the post, for one. We know Circus didn't have the ability to hide flips, because assuming they could kill every Night as well, the hiding would've kicked off either every Night or never. It wasn't the investigative ability of Hep; Harvey Dent embodies the heads side of Two-Face, and being a different slot, Hep probably had its own investigation.
Now, there's also been no kills since Circus died. This could be because there's no mafia left, implying an indy remains. But I don't think that's the case. I think the real reason has to do with multiple factions.
Tails is likely a positive result. Two-Face traditionally flips a coin that has heads on both sides, one side scratched out, but a picture of that in write-ups would be a flatout giveaway. The scratched side, though, would be the one that's an affirmative result.
OS doesn't use role colours randomly. I think that there were two factions. And I think they each had a kill. I think the coin determined whether or not Circus had a night kill. And I think he had a string of good luck. I think he shot X1, and then JTB, and finally Gheb. The lack of coins and the lack of kills, combined with his death, makes me think he was behind them. That would mean Gheb no-shot the whole way through, which I believe to be the case.
I think that JTB's ??? flip was actually Joker, paired with Harley. I think that Circus eradicated them, knocking out their night kill. I don't think there are any roles left with a night kill, because I really think they would've shot last Night, and certainly would've shot the Nights before that. I think we're looking for an indy, or a mafia who has no kill, which is plausible if Circus was their only killer. The only hangup is that you were jailed by Beat the night Gheb died.