Well-known criminal from Cimarron. Approached by the posse because he was 'eyeing' Castor Greeley at The Pale Moon the evening before the tournament. When the posse spoke to him, he claimed (without sharing evidence) that Greeley was a 'demon' when drunk. The posse did research at the local newspaper office and found that Grimm had been jailed for assault the year before, and that the victim was one of the poker players at the tournament.
The day of the tournament, Grimm was again seen at the bar of the Pale Moon, and seemed to have poisoned the drink meant for Greeley's table. A posse member purposefully ran into the server, knocking the drink over. They witnessed George A. Mettery looking very cross at this development. Grimm left the scene before he could be questioned.
After Greeley's murder, the posse approached Grimm and asked if he had known all along that Greeley was a supernatural creature with claws. Grimm laughed and said he didn't consider that Greeley was a werewolf. The posse noted that they never said that he was a werewolf. Questions remain.