Brazil is set to begin three days of national mourning after a Supreme Court justice with a central role in cracking down on corruption died in a plane crash on Thursday. Judge Teori Zavascki, 68, was killed when the light aircraft he was traveling in went down in heavy rain near the town of Paraty. To many, Zavascki was considered a hero for his role in investigating a kickbacks scheme surrounding the state oil company Petrobras. In what is being called the largest corruption scandal in the country’s history, dozens of politicians and business executives have been arrested for taking part in the scheme. Sergio Moro, another judge and central figure in the investigation – which has been dubbed “Operation Car Wash” – told Reuters on Thursday that Zavascki leaves behind a legacy “of serenity, seriousness and firmness in enforcing the law.” “Without him, there would be no Operation Car Wash,” Moro said. While the loss of Zavascki has left many in the country shocked, others have raised questions about whether the plane crash was really an accident, noting that Zavascki’s investigation threatened to snare some very high-level politicians. “It is hard to believe this was a mere accident,” Alan Mansur, the director of Brazil's National Association of Prosecutors, wrote on Twitter.