Senator Marco Rubio’s association with former Congressman David Rivera continues to be a problem for the senator. Sources have told Shadowproof that investigators from both the FBI and IRS looked into Senator Rubio’s connection to a company used by Rivera for what appears to be a scheme to avoid paying taxes on lobbying income.

The company, Millennium Marketing, was paid roughly $1 million in consulting fees by Flagler Dog Track — now known as Magic City Casino — to promote its gambling interests in the state of Florida. As the Miami Herald reported in 2011, Millennium Marketing was supposedly led by David Rivera’s mother and her business partner, but despite the names on paper, the company was the recipient of income for Rivera’s work on behalf of Magic City when he served in the Florida legislature.

While Rivera was listed on a contract to lead a $6.7 million campaign in 2006 to promote slot machines as “Top Leader of Chain of Command,” the compensation for work on that campaign paid by Magic City Casino, totaling $510,000, went to Millennium Marketing.

In 2008, Millennium Marketing received another $460,000 in fees from Magic City after Rivera filed a bill nullifying the successful referendum he campaigned for. After the payment, the bill died giving the exchange all the hallmarks of a shakedown.

During Rivera’s service in the Florida legislature he often worked with Marco Rubio, who was at the time of the slots campaign the Speaker of the Florida House of Representatives. According to people close to the investigation, Rubio was at one point suspected of receiving some of the funds from the Magic City consulting contract.

Though the funds were paid to Millennium Marketing, Rivera ultimately had access to them. Initially Rivera denied getting paid to work on the slots campaign while in the Florida legislature when asked by the Miami Herald, but later revised his financial disclosures to show that he had received a $132,000 loan from Millennium.

Revising official forms was something Rivera had to do multiple times including removing a fabricated connection to the U.S. Agency for International Development (USAID) after the Herald reported he, in fact, never worked there.

Rubio and Rivera’s relationship is both personal and financial. A recent New Yorker profile of Rubio notes that Rivera, along with a man named Ralph Arza, had served as then-Speaker Rubio’s key enforcers in the Florida legislature. Arza was forced to resign after using racial slurs and later plead guilty to trying to intimidate a witness.

David Rivera, meanwhile, went on to the US Congress where he would run into other problems, including numerous federal investigations. The fabricated connection to USAID appears to have been done to justify income that Rivera could not otherwise account for which helped spark an investigation by the FBI and IRS that would eventually include the payments from Magic City Casino to Millennium Marketing.

Rivera faced a separate investigation by the FBI for funding a shadow campaign against his Democratic opponent in the 2010 congressional election that brought him to Congress. The candidate Rivera is alleged to have helped, Justin Lamar Sternad, subsequently plead guilty to accepting illegal campaign contributions.

Rivera’s Congressional seat was redistricted after the 2010 census and Rivera lost the 2012 Republican primary in the new district.

Marco Rubio and David Rivera would have their own collective financial problems, including a house they bought together in 2005. Their home in Tallahassee, Florida was almost foreclosed on for lack of payment before the two sold the property in 2015.

Rivera was also a major player in the Florida Republican Party, as a lobbyist, elected politician, and Executive Director for the Republican Party of Miami-Dade County when Marco Rubio was using a state party credit card for personal expenses. Rubio continually fought attempts to disclose information for his purchases, but now claims all his spending can be inspected — not everyone agrees that is true.

The investigation into David Rivera’s relationship with Flagler Dog Track/Magic City Casino was closed out on the state-level in 2012 [PDF], while the status of the FBI and IRS investigation that includes Rubio remains unknown.

Though Senator Rubio and his presidential campaign team have tried to put distance between Rubio and Rivera, Rivera was spotted at the August Republican presidential debate in Cleveland with Politico reporting that, as of early 2015, Rivera claims the two regularly talk on the phone.

So, the question that remains is — did Senator Rubio receive any part of the Magic City consulting fees? And, if so, how much?