Former French president Nicolas Sarkozy was named a key - and potentially indictable - witness after 12 hours before a judge to answer questions about whether he accepted illegal campaign donations from 90-year-old L'Oreal heiress Liliane Bettencourt.
Ms Bettencourt's former accountant told police she handed over 150,000 euros (£120,500) in cash she was told would be passed on to Mr Sarkozy's campaign treasurer. In July, a magistrate ordered the seizure of Mr Sarkozy's diaries, including his calendars.
The sum, although paling in comparison to US campaign funding amounts, shocked many French citizens because spending on political campaigns is tightly controlled. Individual campaign contributions to candidates are limited to 4,600 (£3,700), and no candidate can spend more than 22 million euros (£17.7 millio) on an entire presidential campaign.
The investigation that has ensnared Mr Sarkozy centres on the finances of Ms Bettencourt, Europe's richest woman and the focus of a long-running family feud over her fortune.
Ms Bettencourt, who was reported to suffer from Alzheimer's disease, has since been placed under legal protection.
Mr Sarkozy's election loss in May cost him his immunity from prosecution. By July, his offices had been raided. The Bordeaux prosecutor, Claude Lapland, said after Thursday's hearing that Mr Sarkozy was given the status of what in France is known as an "assisting witness", with the possibility of facing charges later on allegations of abusing someone in an impaired state, swindling and abuse of confidence.
"Given the extremely strict rules and controls, illegal financing is completely impossible," said Claude Gueant, who was Mr Sarkozy's campaign director at the time, chief of staff and later his interior minister.
Mr Sarkozy entered the Bordeaux court without notice after a decoy vehicle lured away the cameras hoping to catch him on the way in, according to the Sipa news agency. He and his lawyer met investigating judges privately, who handed Mr Sarkozy the special witness status.
They stopped short of filing preliminary charges, as some had expected, and his lawyer Thierry Herzog called the decision a "victory" for the former president. The status is somewhere between a simple witness and a formal suspect. Mr Herzog tried to tamp down interest in the case, saying on RTL radio on Thursday night that the affair "no longer exists".
Sarkozy ally Patrick Balkany, a legislator and mayor, said he spoke to the ex-president after the hearing and "he was content".