In a striking verdict for a money-laundering case associated with the Panama Papers scandal, a Panamanian judge on Friday acquitted all 28 defendants, among them former employees of the law firm Mossack Fonseca, the source of the leaked documents that set off a worldwide furor in 2016.

The verdict came eight years after a partnership of media outlets published an explosive investigation into 11.5 million documents leaked from the Panama-based firm. The leak exposed the offshore banking industry, prompted international tax investigations and brought down heads of state.

Among the original 29 defendants were the shuttered firm’s co-founders, Jürgen Mossack, 76, and Ramón Fonseca, who died in May at age 71 while awaiting the verdict. In her 339-page ruling, the judge, Baloísa Marquínez, said that the case against Mr. Fonseca was dropped because of his death.

Prosecutors had alleged that Mossack Fonseca had created shell companies with the purpose of hiding money earned in illicit activities, and that the firm failed to act with due diligence and take the necessary care when reviewing its clients.

In a written statement published Friday evening, Panama’s judicial branch said that the judge had found that electronic evidence presented by prosecutors did not meet chain of custody protocols and had suffered from authentication issues. It also said that the judge had not found sufficient evidence to hold the accused responsible.