BTG Pactual is under fire after evidence has surfaced that Brazil's largest independent bank has bribed a powerful official with the sum of 45 million reais ($11.5 million) in exchange for political favors. This latest allegation comes just hours after BTG Pactual CEO, Andre Esteves, resigned from his post following his arrest.

In a report with The Wall Street Journal, Brazilian federal police and investigators announced on Monday that they have obtained a document that showed that BTG Pactual had paid the sum of 45 million reais to Eduardo Cunha, who is the speaker of Brazil's lower house of Congress, back in 2013.

The legislation, which was part of an executive decree, reportedly allowed tax credits from the acquisition of failed banks to be used. Cunha allegedly shared the money with other members of his PMDB party, local news source O Globo said.

Reuters added that the news source did not state how it had obtained the information. The documents were reportedly seized from the home of Senator Delcídio do Amaral's aide. Amaral was arrested last week for trying to obstruct a corruption investigation. The senator was arrested alongside Esteves for their involvement in Brazil's corruption probe.

BTG Pactual had denied making the payments and said in an official statement that they are willing to cooperate with the authorities on the matter. Brazil's largest independent bank added that the changes approved the use of those credits started from Jan. 1, 2014, which was later than BTG Pactual's acquisition of the failed bank's assets.

Esteves, who is the CEO of the Brazilian bank, had resigned from his post last week. The Brazilian billionaire's net worth continues to drop as BTG Pactual's shares have lost 32% of its value since his arrest. The billionaire's net worth, which was at its peak at $4 billion in 2013 is now down to $1.9 billion, Forbes said. BTG Pactual sent out letters as an attempt to reassure investors that they have distanced themselves from Esteves. Clients have already begun to pull their money out of the bank. 

The report said that prosecutors have already used the document which outlined the bribes to sway the country's Supreme Court on Sunday in order to extend the detention of Andre Esteves for an indefinite period of time as the investigations continue.

Cunha, on his part said that the accusations made "was a true absurdity." Cunha took to his Twitter account to deny the allegations and said that the entire thing "sounded like a setup."