Officers found the victim with multiple stab wounds and his female colleague bound to a chair at the property in the small northern village of Bullecourt.
The inspector arrived Monday afternoon at the antique dealer's home, accompanied by a colleague, to check his accounts.
Mr. Attal said usually agents were sent on tax check missions on their own, but this time there was backup because there had been tensions during previous visits to the antique dealer's business.
Prosecutors said the businessman tied them up and stabbed the inspector, leaving the colleague "terribly shocked" but otherwise unharmed. A union for tax officials said the case showed that its members had a "potentially dangerous" job