It was the biggest story of their careers and investigative journalists Frederik Obermaier and Bastian Obermayer knew what forces were facing.
"The most important rule was all really be careful regarding who spoke," Bastian said Fred Pleitgen, CNN Monday.
Last year, they had received a hint from an anonymous source up to date, do not yet know the name he or she who asked them if they were "interested in the information."
They would receive would be the largest leak of information on the history -terabits- of magnitude greater than WikiLeaks, Snowden leaking or anything else.
What was immediately apparent is that what would soon become the "roles of Panama" had the potential to embarrass or worse, implicar- to world leaders and individuals sanctioned internationally by connecting them with bank accounts in the outside that supposedly protect their wealth and tax authorities investigating irregularities.
So there is where to play nail polish.
"That was the part where my girlfriend laughed at me when I bought this nail polish," Frederik said.
He had a very serious purpose.
They had already set up a special room for the offices of his newspaper, the German newspaper Sueddeutsche Zeitung. Only a few people had access and computers inside had never been connected to the Internet.
They wanted to be absolutely certain that the treasure had data base would be safe from prying eyes or curious hands, wishing it all go away.
"It was important to keep it secret."
So they went one step further and used the bright nail polish (unknown color) to paint the screws housings computer ... if someone manipulated expected the nail polish will crack and they would know that something was going on.
"You know, in Germany, is not so dangerous," Bastian said. "But still, we have had these thoughts from time to time, yes. Yes, it happened to us."
"We were more concerned about the safety of our colleagues in Russia and Africa and the Middle East."
"Oh, he is the cousin of Bashar al Asad"
It is important to remember, Frederik said that the documents not "just have to see how to avoid or evade taxes."
"For example, there is a case, when we see that talk about the cousin of Bashar al Asad, who was sanctioned in 2008 by the United States, and realize that you are using some of the companies they established, but they kept as customer".
That man is Rami Makhlouf, a powerful man in Syrian politics and business
In 2008 , the United States Department of the Treasury sanctioned , saying it " has used intimidation and his close ties to the Assad regime to obtain commercial advantages inappropriate at the expense of ordinary Syrians."
After three full years , just weeks before the uprising and repression that would lead to civil war in Syria, an email that appears in the data, employee Mossack Fonseca , made it clear that the law firm was pleased to follow doing business with the man . (The term " papers Panama " emerged as a reference to the country where it is based Mossack Fonseca ) .
" From what I can see, there are accusations ( rumors ) , but no facts or pending investigation or prosecution against these people," wrote the employee of the company.
It would not be until the fall, according to The Guardian, the firm broke ties with Makhlouf.
"We saw documents that referred to him as 'Oh, he's the cousin of Bashar al Asad,'" Frederick said.
"There are documents that have been asserted or claimed that he was one of the financiers of the Syrian regime. But apparently did not mind at first."
In a taped interview published shortly after the leak was made public, the co-founder of the law firm, Ramon Fonseca, said: "We do not participate in the activities of the company, nor do we have any responsibility for what the company".
"Remember that due diligence" -which is investigating whether any of the clients or business partners were questionable, as Rami Makhlouf- "is something new," Fonseca said in Spanish. "10 years ago, there was no due diligence. The term was not even known."
Makhlouf CNN contacted through his company, Syriatel, but has not yet received a response.
Fonseca told the Financial Times he does not expect that the leak will lead to "a single legal case", but Frederick said the company co-founder might not want to speak definitively.
Be associated with an account on-the foreign journalists say that according to the documents of Panama, Makhlouf was asociado- alone is not illegal. Journalists do not speculate that the money was used in accounts Makhlouf.
But contravening US sanctions, or sanctions elsewhere, in dealing with a person named "designated" or entity could have serious consequences.
"Although the company is headquartered in Panama, they have offices in the US, so there is the possibility that the US authorities will Mossack Fonseca behind."
"A surreal moment"
Journalists realized from the beginning that the leak "would become a big story" but it was just before publication when they realized the magnitude of it.
"It was a time when we test internally website Süddeutsche Zeitung," Frederick said.
"Our technicians were told they had to try a few minutes before the official publication date."
"And then we saw that Edward Snowden tweeted about this publication ... that was a surreal moment."
"The biggest leak in the history of data journalism just got underway, and is about corruption," tweeted Snowden.
" And for us it was like , whoa !, perhaps it was actually Edward Snowden who tweeted about the project that worked last year? "
"We created our website Süddeutsche English and 24 hours were more English readers that German readers , and that was the first time in the history of this newspaper."