Hobbes' Coin
The first we ever see of Hobbes is the shot of him twiddling what looks like an old silver dollar in his fingers, which we also see him fidgeting with later at the precinct... then Stanton says they found his prints on it at "Noon's place" [I'm assuming that's the cop bar].
The coin looked like he'd had it a long while, as a good luck charm, so...
• How and when did he lose possession of it?
• How did they find it?
• How does it tie him to the murders?