Policemen guard a Bordeaux courthouse where former French president Nicolas Sarkozy is due to appear.

Story highlights

NEW: Former President Nicolas Sarkozy questioned over funding for his 2007 campaign

L'Oreal cosmetics heiress Liliane Bettencourt is suspected of illegally helping him

Bettencourt, 90, is France's richest woman

Sarkozy's former labor minister Eric Woerth and others have also faced scrutiny

Paris CNN  — 

Nicolas Sarkozy may be breathing a bit easier after authorities on Thursday decided not to pursue a formal investigation against the former French president, but rather to treat him as what officials described as a “witness-under-caution.”

The phrase is a technical term that essentially allows a French magistrate to continue to call the former leader to the witness stand in the case over whether L’Oreal cosmetics heiress Liliane Bettencourt and her staff illegally helped him during his 2007 presidential campaign.

Sarkozy still faces the possibility of criminal charges stemming from allegedly illicit campaign donations.

Read more: Attorney: Sarkozy’s home, offices raided

Judge Jean-Michel Gentil questioned the former French leader on Thursday for 12 hours concerning evidence given by 90-year-old Bettencourt’s former accountant, Claire Thibout, CNN affiliate BFM-TV reports.

The Bettencourt scandal has fascinated France since questions about the finances of France’s richest woman emerged last year amid a family feud.

Read more: Why Sarko lost: Personality or policy?

Among the matters probed by investigators were allegations that secret, possibly illegal payments were made to French politicians, including Sarkozy; Eric Woerth, his former labor minister; and members of his party, the Union for a Popular Movement, known as UMP.

Sarkozy lost the diplomatic immunity he held as president when he failed in his re-election bid in May.

CNN’s Pierre Meilhan and Laura Smith-Spark contributed to this report.