Brazilian Senator Flavio Bolsonaro, the leading right-wing challenger to President Luiz Inacio Lula da Silva in next month’s election, is under investigation for alleged corruption and money laundering tied to failed lender Banco Master, according to court documents unsealed on Friday. The probe into the senator, the eldest son of former president Jair Bolsonaro, was ​opened in July by ‌Supreme Court Justice Andre Mendonca, a Bolsonaro appointee who has recently been hailed as a hero by many on Brazil’s right, ⁠including Flavio Bolsonaro himself. Read moreFlavio Bolsonaro launches presidential bid in Brazil despite challenges The development could further shake an already volatile presidential race, with multiple opinion polls showing Flavio Bolsonaro and Lula statistically tied in a simulated second-round runoff. The judge opened the probe at the request of federal police as part of ‌a broader investigation into the failed bank. But details of the investigation only became public after Chief Justice Edson Fachin ordered the ⁠proceedings related to the Banco Master case unsealed late on Thursday. Mendonca complied with Fachin’s request, releasing thousands of pages of court records. Further details and the broader implications of the newly unsealed documents were not immediately clear, as parts of the case, including details of the investigation into Senator Bolsonaro, remained ​under secrecy as police actively investigate. Brazil’s institutions have been shaken by the fallout from the expanding probe and alleged ties between banker ‌Daniel Vorcaro and central bank officials, senior government members, opposition politicians and Supreme Court justices. Probe stems from film financing The investigation into Flavio Bolsonaro stems from questions over an investment he allegedly solicited from Vorcaro, owner of Banco Master, to help finance “Dark Horse”, a film about his father that stars US actor Jim Caviezel. Flavio said Friday he had "nothing to hide" and insisted the financing of the film was "completely legal".