How almost 400 journalists around the world collaborated on Paradise Papers

A few days before the publication of a massive offshore documents leak, a company in Bermuda warned its clients of a security breach. Journalists had been asking a number of questions about confidential company information. But "we are confident that our data integrity is secure," it stated.

The award-winning 2016 Panama Papers project had come out of a major leak of offshore documents, the largest document leak in history. Less than a year since that scandal broke, the Paradise Papers project sheds new light on the offshore world.

For Panama Papers, almost 400 journalists around the world had gained access to the secrets of Panamanian law firm Mossack Fonseca via an anonymous leak.

In March 2017, a group of journalists from nearly 100 global media outlets met in Munich, Germany, with the same intentions - and a little more experience. This time, a Bermuda company, Appleby Global is the company in question.

There were reporters from all continents, press, television, radio. Among the newcomers: two reporters from The New York Times. The newspaper did not participate in the Panama leak but this time they want in.

Among the reporters were Bastian Obenmayer and Frederik Obenmaier, from the German newspaper Süddeutsche Zeitung, who were already familiar faces in the world of collaborative journalism. They are the same reporters who received the leaked batch of documents that led to the Panama Papers.

The two Germans are perhaps the most generous - and practical - journalists on the planet. They have shared two huge databases with their colleagues without asking anything more than discretion. However, their argument for forsaking their own scoop is a good one - they simply can not do it alone.

While the digital information from Appleby wasn't as big - in terabytes - as the Mossack Fonseca leak, there were about two million more documents (13.4 million in total).

The reporters had access to emails, company records and Power Point presentations with confidential data, obtained from two large databases (Appleby, in Bermuda, and Asiaciti Trust, Singapore). They also obtained the secret company registry of 19 jurisdictions.

Marina Walker and Gerard Ryle from the International Consortium of Investigative Journalists (ICIJ) began coordinating the reporting, including secure platforms to communicate, such as the private social network Athena, and two other platforms for deep data searches. Walker and Ryle are well-known for managing collaborative projects including Offshore Leaks (2013), Swiss Leaks (2015), and Panama Papers (2016).

Participating reporters were given tips on how and where to search within the documents, which had been loaded onto password-protected digital platforms. Reporters signed non-disclosure confidentiality agreements to keep the investigation secret until it was ready to be published.

Back at their media outlets, they began to search. It wasn't easy. Unlike the Mossack Fonseca database, Appleby used more sophisticated mechanisms and emails were not always as explicit.

Reporters created online groups, depending on their interests, to focus on different topics and avoid duplicating efforts. For example, one group focused on U.S. politicians, while others looked at Glencore, a multinational mining company. Another focused on Appleby itself.

As the launch approached, increased security measures prevented information leaks by journalists, in the form of encrypted emails and double and triple access verification. A group of journalists from Univision News traveled to the ICIJ headquarters in Washington to receive training in digital search techniques.

Journalists used extreme care when approaching the people they were investigating. In September, ICIJ wrote to Appleby requesting an interview to answer questions about information contained in the documents. A reply warned of possible legal action against the journalists and demanded to know how the information had been obtained. Appleby also asked for copies of the leaked documents.

Another letter sent by ICIJ on Oct. 6 contained 63 detailed questions for Appleby.

A few days later, a group of reporters from Australia, Japan, the United States, Great Britain, and Denmark traveled to Bermuda. They met there with ICIJ reporter Will Fitzgibbon and a film crew from Vox. The idea was to approach Appleby directly by visiting the company's head office.

The group was politely told that no one from Appleby was available.

A few days later Appleby issued a statement saying that it had "thoroughly and vigorously investigated the allegations."

"We are satisfied that there is no evidence of any wrongdoing, either on the part of ourselves or our clients," it wrote.

However, it added: "It is true that we are not infallible. Where we find that mistakes have happened we act quickly to put things right."

On Sunday, in response to the publication of Paradise Papers, Appleby issued another statement accusing ICIJ and its partners of having a "clear political agenda" against the offshore industry and saying it had been the victim of "a serious criminal act."

It went on: "This was an illegal computer hack. Our systems were accessed by an intruder who deployed the tactics of a professional hacker and covered his/her tracks to the extent that a forensic investigation by a leading international Cyber & Threats team concluded that there was no definitive evidence that any data had left our systems."