Mr Gentil is the most prominent of the three judges conducting the investigation.

BBC: Sarkozy Bettencourt: Lead judge receives death threat

Judge Jean-Michel Gentil questioned the former French leader in November for 12 hours concerning evidence given by Bettencourt's former accountant, Claire Thibout, BFM-TV reported.

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Magistrate Jean-Michel Gentil, who leads the inquiry, unexpectedly summoned Mr Sarkozy for a face-to-face encounter with Mrs Bettencourt's butler, Pascal Bonnefoy, in the city of Bordeaux.

BBC: Nicolas Sarkozy to be investigated in Bettencourt scandal

"This search, as expected, proved to be futile given that all required elements had been sent to the magistrate (Jean-Michel Gentil) a fortnight ago, " Herzog said.

CNN: Attorney: Sarkozy's home, offices raided

The 26-year-old will face a big opponent in Pascal Gentil.

CNN: South Korea: More Than Kicks

"Every night we watch videos of Gentil, " says Choi.

CNN: South Korea: More Than Kicks