The firm gained global notoriety in 2016 when it found itself at the centre of the Panama Papers affair, which uncovered the activities of the offshore finance industry.

According to the leaked papers, Mossack Fonseca set up more than 214,000 shell companies around the world, some of which were found to have been used for illegal purposes, including fraud and tax evasion.

[11] His father, Erhard Mossack, was a mechanical engineer who had served as a combat soldier with the rank of Rottenführer (senior corporal) in the Waffen-SS, the armed wing of the Nazi Party's Schutzstaffel, during World War II.

[14][15] Germany's Federal Intelligence Service, said in 2016, when contacted by journalists, that they had documents related to Erhard Mossack but would not share any information, owing to possible security risks.

[14][16] They built a global group of 600 employees and 46 subsidiaries, across countries including the Bahamas, the British Virgin Islands, Hong Kong, Switzerland, Jersey, Luxembourg, and the US, specifically the states of Wyoming, Florida, and Nevada.

[18] Mossack's holdings, according to the files obtained by the International Consortium of Investigative Journalists (ICIJ), include a teak plantation and other real estate, an executive helicopter, a yacht named Rex Maris and a collection of gold coins.

Mossack told the Wall Street Journal that the intermediary banks that his firm worked with — and who represent the final recipients of the shell companies — should have done better reviews of their clients: "Our brand needs to be protected.

[28] According to court papers filed on 15 October 2019, Mossack and Fonseca "are the subjects of an FBI Investigation in the Southern District of New York" and are "defending criminal charges against them in Panama.

[32] Investigators began focusing on the law firm after finding an array of apartments in the names of relatives of an imprisoned politician, the New York Times reported.