In a move not often seen in the pharmaceutical industry, the head of a large drugmaker is being investigated by authorities over drug safety. Jacques Servier, who founded Servier Laboratories, is under investigation as part of a probe into the Mediator diabetes drug, which has been blamed for at least 500 deaths in France, Reuters reports.

Specifically, the 89-year-old Servier is being investigated on suspicion of dishonest practices, deception over drug quality and falsely obtaining authorization to sell Mediator, which was often prescribed as an appetite suppressant by diabeties, his lawyer tells Reuters. Five companies under the Servier corporate umbrella are also under investigation. Servier is France’s second-largest drugmaker.

The pill was linked to heart-valve damage and government investigators have previously said the risks were deliberately concealed. As many as 5 million people took the pill between 1976 and November 2009, when it was withdrawn in France, but that was several years after it was yanked in Spain and Italy. French health inspectors say Mediator should have been withdrawn a decade earlier.

The French health ministry says at least 500 people died of heart-valve trouble in France, although other estimates have placed the death toll closer to 2,000. The active ingredient, benfluorex, is closely related to fenfluramine, one half of the infamous fen-phen weight-loss cocktail. Fenfluramine was withdrawn from the US market in 1997 after being linked to heart-valve damage.

The probe was prompted by the disclosure of a 1998 letter by French doctors indicating concern that the drug could cause heart-valve damage (back story). The drugmaker denied misleading authorities and patients, and has acknowledged 38 deaths linked to the drug, but says its pill caused only four.

As for Servier, who was awarded France’s national merit medal, the Legion d’Honneur less than a year before the drug was pulled, he was ordered to post bail of about $5.4 million and guarantee possession of another $8 million before December 15. The Servier companies must post $36 million and an added guarantee of $53 million. Meanwhile, a hearing will take place next week involving 150 civil lawsuits.

The health scandal is shaking confidence in the public health system. Health minister Xavier Bertrand was linked to the controversy after reports that two of his former advisers - a doctor and a public health expert who was in charge of research at the ministry - had once worked for Servier. He claimed he had no knowledge they ever worked for the company.

Consequently, France may soon require that conflicts of interest are publicly disclosed by directors and experts at regulatory agencies, and made available publicly, Nature Medicine writes. Any failure to do so would incur sanctions, including fines of up to $43,000.

One unanswered question is why Mediator remained on a list of drugs that qualified for state rebates to patients. One estimate found that France’s social security services spent $586 million) to reimburse people who bought the pill during its last 10 years on the market. “It’s now up to us to explain ourselves,” Temime told Reuters. “It goes without saying, but people who have been put on trial are innocent until proven guilty.”