Tapped phone calls between ex-President Luiz Inacio Lula da Silva and prominent public figures suggest attempts were made to curry favor for the former leader in his judicial woes, according to the magistrate in charge of the sprawling corruption investigation at Brazil’s state-run Petrobras oil company.

Judge Sergio Moro released nearly 50 audio recordings Wednesday, hours after President Dilma Rousseff appointed Silva as her chief of staff, a move that critics called an attempt to help shield him from potential detention as part of the corruption probe.