A German newspaper that obtained leaked files from a Panamanian law firm detailing offshore financial dealings has published what it said is a manifesto from its anonymous source.
The self-described "John Doe" described having been moved to act by "the scale of the injustices", the documents show.
The daily Sueddeutsche Zeitung was offered the leaked data over a year ago through an encrypted channel by the source, and started publishing material last month along with other outlets it shared the information with.
It said it has now received a manifesto from its source, though it did not specify how and when. It could not immediately be reached for further details.
The repercussions of the leaked documents from law firm Mossack Fonseca have been far-ranging.
The uproar led to the resignation of the prime minister of Iceland, and brought scrutiny to, among others, the leaders of Argentina and Ukraine, Chinese politicians, Russian president Vladimir Putin and his friends.
The piece published on Friday says the papers "show beyond a shadow of a doubt that although shell companies are not illegal by definition, they are used to carry out a wide array of serious crimes that go beyond evading taxes".
Its author writes: "I decided to expose Mossack Fonseca because I thought its founders, employees and clients should have to answer for their roles in these crimes, only some of which have come to light thus far."
The manifesto says "a new global debate has started, which is encouraging".
It does not shed light on how the source obtained the documents.
Its author says: "For the record, I do not work for any government or intelligence agency, directly or as a contractor, and I never have," and adds that the reason for sharing the documents was "not... any specific political purpose, but simply because I understood enough about their contents to realise the scale of the injustices they described."
The author "would be willing to cooperate with law enforcement to the extent that I am able".