At the time, the essential man of the Sarkozy presidency, now 77 years old, was a candidate in Hauts-de-Seine.

An election campaign must respect a spending limit. In this case, Mr. Guéant should not exceed the sum of nearly 67,000 euros in order in particular to be able to obtain reimbursement of his personal contribution of more than 30,000 euros.

For the prosecution, Mr. Guéant knowingly understated his accounting items and, ultimately, received a refund.

A four-page letter is at the heart of this investigation.

In this letter, sent on January 3, 2012, Pierre-Christophe Baguet, UMP mayor (now LR) of Boulogne-Billancourt and outgoing deputy of Hauts-de-Seine, announced that he would support Claude Guéant to succeed him in the National Assembly. He had attached the declaration of candidacy of the latter.

The prosecution accuses them of having sought to have Boulogne-Billancourt finance electoral propaganda expenses in support of Claude Guéant’s candidacy.

“I am not guilty of anything,” said Mr. Guéant, graying hair, standing straight at the stand in his dark suit.

«This letter is first of all a personal character», also assured Mr. Baguet, confident that he wanted to explain the reasons for his departure as a deputy.

The criminal court has two days to determine the nature of this letter – approach of the mayor or electoral character? -, its conditions of realization – Mr. Guéant had he given his agreement? – and his financing.

For Mr. Guéant, who is also on trial for illicit campaign financing, this letter had «no electoral character» requiring it to be included in his campaign accounts, because it was «the intervention of a third party» to support it, an intervention to which Mr. Guéant claims not to have given «a clear agreement».

The UMP then financed part of it: more than 5,000 euros.

«I could very well have paid nothing at all», estimates the one who was director general of the national police and who faces today up to five years of imprisonment and 375,000 euros in fine. But «very quickly, I had the intuition that this case was likely to cause problems (…) and I did not want to start my campaign with a controversy», details Mr. Guéant.

On the bench of the defendants also appear two employees of the town hall, the manager of a printing press as well as the printing press, for another aspect of the case concerning the offense of favoritism.