Deltan Dallagnol, 40, the coordinating prosecutor on the investigation, said in a video on Twitter that his 22-month-old daughter had been diagnosed with developmental delays that "will require our very intense dedication as parents."
Attorney General Augusto Aras later announced he was renewing Operation Car Wash for another year, ending doubts over its future.
It will be led by Dallagnol's longtime colleague Alessandro Oliveira.
The operation has upended Brazilian politics and business since it was launched as a money-laundering probe based out of the southern city of Curitiba in 2014.
Using an aggressive strategy of arrests and plea bargains, it steadily pried the lid off a massive corruption scheme in which politicians and business executives plundered billions of dollars from state-run oil company Petrobras.
The investigation led to the jailing of some of the biggest names in Brazil, including former president Luiz Inacio Lula da Silva.
Convicted participants' tell-all confessions in exchange for lighter sentences also sent tremors around Latin America, as it emerged that a laundry list of presidents and other powerful politicians had taken huge bribes from one of the main players in the scheme, the construction company Odebrecht, in exchange for juicy public contracts.
But critics accuse the operation of playing politics, particularly after internal communications were leaked to the media that appeared to show investigators conspiring to keep Lula, a leftist icon, from staging a come-back in Brazil's 2018 presidential race.
Dallagnol, an Evangelical Christian and amateur surfer, was one of the most visible faces of the investigation, along with the federal judge who presided over it, Sergio Moro.
Moro left the judiciary to become justice minister under far-right President Jair Bolsonaro after the latter won the 2018 election.
However, he quit the government in April, accusing Bolsonaro, who ran on an anti-corruption platform, of interfering in police investigations targeting the president's inner circle.