PARIS - A Renault SA security employee has divulged the name of a person he says is the informer that prompted that car maker to believe it had been the victim of industrial espionage, the Paris prosecutors' office said, as investigators dig into the circumstances behind the bizarre affair.

Dominique Gevrey, an employee of Renault's security department, has been in detention since last weekend, as prosecutors have placed him under investigation for alleged fraud, according to prosecutors. In particular, the investigators are trying to find out how Renault's security department spent some €700,000 (about $970,000) as part of its internal industrial espionage probe, prosecutors say, reported The Wall Street Journal.

The probe led Renault in January to fire three managers for allegedly selling strategic information about the company's electric vehicle program. On Monday, however, Renault acknowledged the three were innocent and apologized to them.

Mr. Gevrey "gave a name, but it hasn't been verified," a person at the Paris prosecutor's office said on Friday. Mr. Gevrey's lawyer, Jean-Paul Baduel, wasn't immediately available for comment on Friday. He has previously said that Mr. Gevrey had a Swiss bank account where money was set aside to pay an informant on Renault's behalf. He has said Mr. Gevrey hasn't engaged in any wrongdoing. Renault and prosecutors haven't commented on Mr. Baduel's assertion about the Swiss bank account.

A Renault spokeswoman declined to comment on Mr. Gevrey's having given a name to the prosecutor. "There's an investigation going on," she said. "We're not allowed to comment."

Renault first launched its investigation into alleged espionage last summer after receiving an anonymous letter accusing one of the fired managers of taking bribes. The company then announced in January that it had been the victim of espionage; at the time, it pointed to secret bank accounts that the three senior managers allegedly held in Switzerland and Lichtenstein as proof that the managers had accepted bribes.

Renault later said that the company based its information about the alleged bank accounts on its internal security department, which had, in turn, received the information from a secret informer. Prosecutors, however, ended up finding no evidence of any bank accounts, leading Renault to climb-down on its accusations.

Now, both Renault and French prosecutors say they are trying to find out whether the company was tricked into spending money to follow up on what turned out to be a bogus espionage case. The Paris state prosecutor, Jean-Claude Marin, said earlier this month that Renault had paid €300,000 to cover the cost of its probe, and had an additional €400,000 in bills waiting to be paid. Mr. Marin said the evidence pointed to Renault having been the victim of an organized attempt to defraud it.

To take responsibility for the debacle, Renault's Chief Operating Officer Patrick Pelata offered his resignation Monday, but Chief Executive Carlos Ghosn declined to accept it.

The French government, which owns 15% of the company, is still not satisfied with the response, however. Finance Minister Christine Lagarde said Friday that the Renault's top management should "face the consequences of an analysis of who was responsible." Speaking on Europe 1 radio, she said: "First of all I want compensation to be awarded and reinstatement offered…The employees have turned out to be victims in this affair."

On Thursday, Ms. Lagarde and Industry Minister Éric Besson demanded that an audit into Renault's management identify "the origin of the dysfunctions recently observed at the core of the company," according to a joint statement by the ministers. "This audit will need to come up with results quickly," it added. A finance ministry official said this meant by the end of April.