Buenos Aires: A businessman who has admitted paying “contributions to election campaigns” during the presidencies of Nestor and Cristina Kirchner could testify in a major corruption case roiling Argentina’s political and business worlds.

Juan Carlos de Goycoechea, who once headed the construction and energy group Isolux Corsan in Argentina, surrendered to police on Friday and asked for protection under an “accused collaborator” program requiring an admission of having paid bribes.

According to judicial sources quoted in the local press, he said the Planning Ministry — which oversaw public works during the successive Kirchner governments, from 2003 to 2015 — applied “pressure to contribute to election campaigns.”

But the amounts involved, he insisted, were much lower than the $12.8 million (Dh47 million) cited by presiding judge Claudio Bonadio.

Isolux fired de Goycoechea in March 2017, after an internal investigation of alleged irregularities.

Prosecutors say the alleged bribes — paid by businessmen in an elaborate collection system that funnelled money to the Casa Rosada, home to the executive mansion and offices, or to the Quinta de Olivos presidential residence — could total $160 million.

Since the investigation came to light on Wednesday, 16 businessmen and ex-officials have been detained in dozens of raids. They face charges of conspiracy in a bribery and kickback scheme that is being compared in Argentina to the far-reaching Car Wash investigation in Brazil.

The key evidence in the Argentine case, involving a total 36 defendants, lies in eight modest spiral notebooks crammed full of minutely detailed notations.

They were kept over a decade (2005-2015) by Oscar Centeno, a retired army officer who served as a driver for Roberto Baratta, a former No. 2 at the Planning Ministry who is now under arrest.

The 29-page indictment states that businessmen made illicit payments totalling some $35.6 million between 2008 and 2015.

Centeno’s notes describe his many trips with Baratta to deliver bags full of dollars to destinations including the residence of Cristina Kirchner. She has been summoned for questioning on August 13.

Centeno was arrested Wednesday but freed Friday after entering the “accused collaborator” program, which would provide legal protection for him, his partner and their 13 children.

Centeno has admitted being the author of the eight notebooks, though he told the judge that he burnt the originals last May on a backyard grill, according to the press.

The judge obtained copies from Diego Cabot, a journalist with the newspaper La Nacion, who had temporary access to the originals after a friend, retired policeman Jorge Bacigalupo, handed them to him.