The "John Doe" whistleblower behind the leaked documents that became known as the Panama Papers has spoken out via an interview with Germany's Der Spiegel, arguing that the EU should step in to ensure justice for murdered journalists Daphne Caruana Galizia and Ján Kuciak, and "to deliver rule of law in Malta".

In the interview, the whistleblower laments that more has not been done to tackle the use of shell companies to stop flows of money, including money that is helping fund the Russian war on Ukraine.

And they note that they are likely to remain un-named until such time that they feel it may be safe to come out of the shadows; although this may not be possible given how, for example, Russia has acted against those seeking to shine a light on the finances of the Kremlin.

"Putin is more of a threat to the United States than Hitler ever was, and shell companies are his best friend. Shell companies funding the Russian military are what kill innocent civilians in Ukraine as Putin's missiles target shopping centers. Shell companies masking Chinese conglomerates are what kill underage cobalt miners in the Congo. Shell companies make these horrors and more possible by removing accountability from society. But without accountability, society cannot function," the whistleblower says in the interview.

And on the risk of Russia seeking revenge should the whistleblower's identity become known, they said: "It's a risk that I live with, given that the Russian government has expressed the fact that it wants me dead."

"Before Russia Today's media presence was curtailed due to Russia's attack against Ukraine, it aired a two-part Panama Papers docudrama featuring a "John Doe" character who suffered a torture-induced head injury during the opening credits, after which a cartoon boat sailed through the pool of his blood, as though it were the Panama Canal. However bizarre and tacky, it was not subtle. We have seen others with connections to offshore accounts and tax justice resort to murder, as with the tragedies involving Daphne Caruana Galizia and Ján Kuciak. Their deaths affected me deeply, and I call upon the European Union to deliver justice for Daphne and Ján and their families. And to deliver rule of law in Malta, one of Mossack Fonseca's former jurisdictions."

The interview took place with the same two journalists to whom the whistleblower originally handed over some 2.6 terrabytes of data when they then worked at the Süddeutsche Zeitung. That data was subsequently shared with the International Consortium of Investigative Journalists (ICIJ), whose expose brought down political and business leaders across the globe.

It also brought down the law firm from which the data was leaked. Mossack Fonseca in 2018 said it was closing because of the financial and reputational damage that the leak of data caused.