Francesco Saverio Borrelli, the former prosecutor whose landmark anticorruption investigation in the early 1990s helped sweep away Italy’s ruling class and transform its politics, died on Saturday in Milan. He was 89.

The Istituto dei Tumori, the hospital where he had been treated for cancer, confirmed his death.

Mr. Borrelli, who served in the Italian judiciary for 47 years, became a national symbol of the rule of law during the vast anticorruption investigation known as Mani Pulite, or Clean Hands, which he led from 1992 to 1994.

The investigation led to 1,281 convictions and the indictment of a former prime minister, who fled the country. It put an end to Italy’s First Republic, the political order that took power after the fall of Fascism.

“Others would have given in to political pressure, but Saverio was one of a kind,” said Gherardo Colombo, a prominent Italian prosecutor who worked closely with Mr. Borrelli. He was, he added, “the right man, in the right place, at the right time.”