All fines imposed under sections 3701 to 3704 shall be appropriated to the repair of such ways. The court imposing them shall appoint one or more agents to superintend their collection and application. Within 3 months after collection, they shall make return of their doings to the clerk of the court, to remain on file for the inspection of those interested, and subject on their motion to be audited and corrected by the court. If an agent is guilty of gross neglect of duty or fraudulently misapplies or retains the fine, he forfeits to the town double its amount, to be recovered by indictment.