in São Paulo The death in a plane crash of a Brazilian supreme court judge has thrown the Petrobras corruption investigation that has rocked the country’s political establishment into confusion.

Teori Zavascki died with four other people when the private plane taking him from São Paulo to the coastal resort town of Paraty in Rio de Janeiro state crashed into the sea 2km short of the town’s airport on Thursday afternoon.

Zavascki was the supreme court justice overseeing the three-year long inquiry into Petrobras which has uncovered a scheme operated by the country’s political elite and leading members of the business community to defraud the state-controlled energy giant of billions of reais.

Next month, he was scheduled to publish plea-bargain agreements signed by 77 executives from Odebrecht, Brazil’s biggest construction company, that are expected to implicate current president Michel Temer and his two immediate predecessors, Dilma Rousseff and Luiz Inácio Lula da Silva, in wrongdoing.

Speculation

Mr Temer must now select a replacement for Zavascki. According to the court’s internal regulations, his substitute will inherit supervision of the Petrobras investigation, though leading jurists have already called for it to be passed to one of the current justices.

The sudden death of a key figure in the inquiry at such a delicate moment led to an explosion of speculation on social media that the plane was deliberately brought down, even before the wreckage was pulled from the sea.

Speaking on radio on Friday, Zavascki’s son Francisco called for a thorough investigation. “Personally I am rooting for it to have been an accident. It would be very bad for the country to have a member of the supreme [court] assassinated,” he said.

In May of last year Francisco posted on his Facebook page: “If something happens to someone from my family, you already know where to look.”

Asked about his son’s post, Zavascki confirmed he had received threats but dismissed them as “nothing serious”.

Federal police

One of the lead investigators from Brazil’s federal police in the Petrobras case seemed to express doubts that Zavascki’s death was an accident. On his Facebook page detective Márcio Anselmo wrote: “Now, on the eve of the confirmation of the Odebrecht plea bargain, this ‘accident’ must be fully investigated.” He later removed the line from his post after it went viral.

Brazil’s federal prosecutions service, which has led the Petrobras inquiry, has already launched an investigation into the crash.

There was rain and heavy cloud in Paraty at the time. Brazil has one of the world’s largest fleets of private planes and helicopters, and accidents are frequent. Official data shows there were 123 aviation accidents and 57 fatalities in 2015.

A number of leading public figures have died in air accidents in Brazil in recent decades. In 2014 presidential candidate Eduardo Campos died when the private jet he was travelling on crashed in the port city of Santos.