Jair Bolsonaro’s murky family finances have come under renewed scrutiny after claims the Brazilian president and close relatives used cash to pay for more than 50 properties worth millions of dollars. The allegations – the result of a seven-month investigation by the Brazilian news group UOL – suggest that between 1990 and 2022, members of the Bolsonaro clan repeatedly used large sums of cash to pay for flats, houses and plots of land in cities including Rio de Janeiro and São Paulo. “Jair Bolsonaro and his closest relatives bought 107 properties over the last 30 years and at least 51 of those properties were bought with cash,” UOL claimed, citing hundreds of notarial and real estate deeds as well as interviews with sellers. One property – a “mansion” in rural São Paulo – was allegedly acquired for 2.67m reais ($525,000) by Bolsonaro’s brother-in-law, who reportedly uses the nickname “Jagunço” (hired gun). “The president needs to explain the origin of this money. Where did this money come from?” said Juliana Dal Piva, one of the reporters behind the exposé. Bolsonaro, who won power in 2018 by pledging to fight corruption, reacted tetchily to the reports, which he blamed on “a news outlet without the slightest credibility”. “What’s the problem in paying for a property in cash?” Bolsonaro reportedly asked, shrugging off the possibility of an investigation. “Investigate, my God,” he told reporters. Leonardo Sakamoto, a UOL columnist, wrote: “You don’t need to be a financial genius to understand that the use of large sums of cash to buy property is a means of laundering resources of illegal origin.” Dal Piva said one case involving Bolsonaro’s senator son, Flávio Bolsonaro, involved the cash payment of 638,000 reais for two flats in Rio’s beachside Copacabana neighbourhood. “That’s more than $100,000 – it is an extraordinary amount … and there are several such transactions involving 100,000, 200,000 or 500,000 [reais]. They have never explained the origin of this money and why they decided to use cash instead of making an electronic transfer or paying by check,” said Dal Piva, the author of a forthcoming book about the president’s financial dealings called Jair’s Business: The Forbidden History of the Bolsonaro Clan. The book, which will be published in September by one of Brazil’s top publishers, promises to lift the lid on an allegedly long-running corruption scheme involving Bolsonaro and his politician sons. The Bolsonaro family has for years been dogged by allegations of involvement in an illegal racket known as “rachadinha”, involving the embezzlement of the wages of employees. They have rejected those claims. This week’s revelations come with Bolsonaro facing an uphill struggle to secure a second four-year term when Brazil chooses its next president on 2 October. The far-right former army captain is trailing badly in the polls behind his leftist rival, the ex-president Luiz Inácio Lula da Silva. In the first presidential debate, on Sunday Bolsonaro accused Lula of leading “the most corrupt government in Brazilian history”. But on Tuesday it was Bolsonaro facing uncomfortable questions. Dal Piva said she was not surprised the president had declined to explain the use of so much cash. “He’s afraid of this story,” she said. “That is why he doesn’t respond.”