Well, read the rule:
Game End and Scoring
A case is solved as soon as all tiles of a crime/color have been taken from the columns. The player with the highest total value of Evidence Tiles of this crime receives the Loot (Bonus) Disk and displays it face up in front of him. In the case of a tie, the Loot (Bonus) Disk is returned to the box and not scored.
Seems pretty clear to me. Wouldn't be the first time Board to Death got rules wrong.