A violent mafia-style gang in Nigeria linked to murder and fraud has infiltrated the country's political system and launched a global scamming operation well beyond Nigeria's borders, according to thousands of hacked documents and testimonies seen by the BBC.

The "Black Axe" gang has been operating for decades in Nigeria and is among the country's most-feared organised crime syndicates. Membership of these syndicates, known as "cults" or "fraternities", is outlawed in Nigeria.

For the past two years, BBC Africa Eye has been following the Black Axe, speaking to former members and combing through thousands of documents that appear to have been hacked from a number of prominent members of the group. It was not possible to verify the entire cache, but key documents were verified by the BBC.

Among our findings were emails that suggest a prominent Nigerian businessman and 2019 APC party candidate for political office, Augustus Bemigho, was a senior member of Black Axe and was involved in orchestrating fraudulent internet scams netting millions of dollars.