The 11.5 million documents taken from the Panamanian law firm, Mossack Fonseca, by a source who has not been identified have been the subject of news coverage around the world since April, shedding new light on the murky world of offshore finance. The Panama Papers project, organized by the international journalists’ consortium, has involved more than 400 reporters around the world and has set off criminal investigations in many countries.

Mossack Fonseca has said it should not be blamed for wrongdoing by its customers. “We merely help incorporate companies, and before we agree to work with a client in any way, we conduct a thorough due-diligence process,” the firm said in a statement. The statement noted that the firm had not been charged with criminal wrongdoing in nearly 40 years of operation.

But the journalists found that Mossack Fonseca had sometimes missed or ignored evidence of criminal investigations or charges against its clients. Though the records show that the law firm did scrutinize many of those who sought its services, its reviews were often belated or incomplete, according to the articles’ main author, Will Fitzgibbon, who works at the consortium’s office in Washington.

Several major figures examined in the new Panama Papers reports have previously been accused of wrongdoing, and some are under criminal investigation or have been charged. But the details of their use of shell companies had not previously been disclosed.

The consortium identified 37 companies created by the law firm that had been named in court actions or government investigations involving natural resources in Africa. All told, Mossack Fonseca’s files revealed offshore companies that were established to own or do business with oil, natural gas and mining operations in 44 of Africa’s 54 countries.