Glenn Greenwald's (https://en.wikipedia.org/wiki/Glenn_Greenwald) The Intercept has published leaked conversations (from 2015-2018) between prosecutors and Sergio Moro, the judge in Lula's case. The leaks reportedly comprise "over 1700 pages" of Telegram conversations.

In the small portion of the leaks published so far, Moro suggests how operation Carwash should proceed, indicates possible witnesses, directs and counsels the prosecution on how to present evidence and even anticipates his rulings. Lula's defense points out this is grounds for annulment of the entire case. Brazil is currently split in polarization and the leaks are taking precedence over other political matters which until last week dominated the discourse (such as the proposed welfare reforms).

Moro and the Prosecutor's Office did not deny the conversations took place but Moro did not explicitly confirms the contents are true. The Intercept and other journalists are being attacked about the 'illegal' nature of the leaks, mostly, which makes them unusable for criminal prosecution of Moro and prosecutors but can still be used politically and/or might result in overturning many Carwash sentences - including Lula's.

About Telegram and the leaks:

Telegram states "there's no evidence of any hack. Most likely to have been either malware or someone not using a 2-step verification password."

Today, however, someone hacked into a Brazil's Public Prosecutor's Office Telegram group - at first impersonating a member. They later revelead that they were an impostor and stated that they were the hacker responsible for the leaks. If this is correct, the hacker (who states to not be politically motivated and "just an IT guy") can still (reliably?) gain access to Telegram's conversations and is also capable of impersonating people.