In July, Mediapart began the publication of a series of investigative articles about the very close and longstanding links between Franco-Lebanese arms dealer Ziad Takieddine and the inner circle of advisors and aides surrounding Nicolas Sarkozy - before and after he became French president. Takieddine is a key witness in an ongoing French judicial probe into suspected illegal party financing through commissions paid in a major French weapons sale, and Mediapart's revelations raise disturbing questions about other deals he was involved in. In a brief interview with Mediapart in July, Takieddine declared: "I'm a clean man and you're dirty. You're one of the filthy who are most productive in the muck." Here, Mediapart Editor-in-Chief Edwy Plenel sets out the key issues exposed by the investigations, and argues why an unprecedented chain of corruption is strangling France's institutions.