The leaked messages show that Mr. Moro often overstepped his role as a judge — someone who is supposed to be impartial and free from bias — to act as a consigliere for the prosecution. He offered strategic advice to prosecutors: they should, for example, reverse the order of various phases of the investigation; think again about a particular motion they were planning to file; speed up certain processes; slow down many others. Mr. Moro passed on information about a potential new source to the prosecution; scolded prosecutors when they took too long to stage new raids; endorsed or disapproved of their tactics; and provided them with advance knowledge of his decisions.

The revelations have shed new light on Mr. Moro’s conviction of former President Luiz Inácio Lula da Silva, in 2017. (In Brazil, jury trials are restricted for offenses against life, such as homicide and infanticide. In other criminal cases, the same judge who oversees the investigation is also the one who judges and sentences the accused.) The left-wing politician, who ruled the country from 2003 to 2010, is currently in jail, having been convicted on charges of corruption and money laundering. He was deemed ineligible to run for president precisely at a time when polls showed him to be the front-runner in the 2018 race. Mr. da Silva’s convenient detention cleared the way for the election of the far-right Jair Bolsonaro, who then — wait for it — gracefully appointed Mr. Moro as Brazil’s justice minister.

According to material published by the news site The Intercept Brasil, over the course of the investigation, Mr. Moro meddled in matters of press coverage and worried about how to get the public’s support for the prosecution. “What do you think of these crazy statements from the PT national board? Should we officially rebut?” he once asked federal prosecutor Deltan Dallagnol, referring to a statement by Mr. da Silva’s Workers’ Party in which the indictment was deemed a political persecution. Notice the use of the word “we” — as if Mr. Moro and Mr. Dallagnol are on the same team.

This is all, of course, highly immoral — if not downright illegal. It violates nothing less than the Universal Declaration of Human Rights, which says: “Everyone is entitled in full equality to a fair and public hearing by an independent and impartial tribunal, in the determination of his rights and obligations and of any criminal charge against him.” Under Brazil’s Criminal Procedure Code, judges are supposed to be neutral arbiters and cannot give advice to any of the parties in a case. Mr. Moro also violated many provisions of the Brazilian Code of Judicial Ethics, particularly one that says the judge should maintain “an equivalent distance from the parties,” avoiding any kind of behavior that may reflect “favoritism, predisposition or preconception.”

When the leaks were first reported, the Car Wash task force and Mr. Moro did not dispute the authenticity of the material, arguing instead, per Mr. Moro, that the messages showed “no sign of any abnormality or providing directions as a magistrate.” He also expressed dismay at the “lack of indication of the source of the person responsible for the criminal invasion of the prosecutors’ cellphones” — even though The Intercept’s reasons for not disclosing its source are obvious.