In testimony made to Judge Claudio Bonadio, he claimed he was "pressured" to "close cases against the Kirchners", referring to former presidents Néstor and Cristina Kirchner, court sources told Perfil.
He pointed to former spy Antonio "Jaime" Stiuso and Javier Fernández, a member of the General Auditor's Office, whom he described as a "judicial operator" for the Kirchners.
On Friday, the disgraced former judge, who is known for his extravagant lifestyle and occasional appearance on commercial television, told journalists through the electronic doorbell of his apartment that his life was in danger.
"I'm not leaving my apartment for at least one month", he said. Oyarbide confirmed he had been granted additional personal security.
Oyarbide resigned from the judiciary in 2016 because of pressure over the many complaints, some criminal, made against him.
Last week, his name appeared in the series of photocopied notebooks obtained and published by La Nación newspaper, with detailed information regarding the “collection mechanism” of hundreds of millions of dollars in bribes that went all the way to the Executive.
The revelations sparked arrests and raids throughout Buenos Aires City and province last week, targeting both former members of the Kirchnerite administrations and businesspeople.
Over 20 people have now been arrested since the operation first began.
The investigation, led by controversial federal Judge Bonadio and federal Prosecutor Carlos Stornelli accuses Néstor Kirchner and his wife and successor as president, Fernández de Kirchner, of leading a criminal scheme to appropriate illicit funds stemming from kickbacks paid by companies looking to secure public works projects.
At the centre of the probe is Oscar Centeno, a former Army sergeant who previously worked as the chauffeur of Roberto Baratta, a sub-secretary of the Federal Planning and Public and Investments Ministry during the Kirchner years.
Baratta was considered to be the ‘right hand man’ of Julio De Vido, the embattled former federal planning minister who has been accused of orchestrating a massive kickback scheme around public works projects that defrauded the state of hundreds of millions if not billions of dollars from 2003 to 2015.
On Thursday, Oyarbide denied any personal connection with De Vido and said the dates written in the notebooks are wrong.