We study the impact of an investigation into collusion and corruption to learn about the organization of cartels in public procurement auctions. Our focus is on Montreal’s asphalt industry, where there have been allegations of bid rigging, market segmentation, complementary bidding and bribes to bureaucrats, and where, in 2009, a police investigation was launched. We collect procurement data and use a difference-in-difference approach to compare outcomes before and after the investigation in Montreal and in Quebec City, where there have been no allegations of collusion or corruption. We find that entry and participation increased, and that the price of procurement decreased. We then decompose the price decrease to quantify the importance of two aspects of cartel organization, coordination and entry deterrence, for collusive pricing. We find that the latter explains only a small part of the decrease.