MIAMI (CBSMiami) — Former Hialeah Mayor Julio Robaina and his wife Raiza were arraigned Friday morning on federal tax evasion charges.

Their attorney entered a not guilty plea and the court recommended that Robaina’s wife get a separate attorney.

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The Robainas are charged with fraud, conspiracy and falsifying documents.

Outside court, Julio Robaina told reporters, “Today is the first step of a process. We believe in the justice system. We know that when the facts are told, and we have our day in court, we will be vindicated, our name will be cleared.”

Following their surrender and arrest last week, Julio, 48,  received a $250,000 surety bond and Raiza, 39, received a $100,000 surety bond. Additionally, both were required to surrender their passports and all travel is limited to Central Florida where they have a child in college.

The couple can’t possess a firearm or sell or buy any property unless it’s to pay for their attorney fees.

The charges are the result of an investigation, first reported by CBS4 News in 2011, which stems from allegations made against Robaina by Luis Felipe Perez, who plead guilty in 2010 of operating a $45 million Ponzi scheme.

Click Here to read the indictment filed against the Robainas.

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Perez, known by the nickname Felipito, has been cooperating with federal prosecutors in an attempt to reduce his ten-year prison term.

The Robaina investigation centers on a series of loans Robaina and his wife made to Perez over an 18-month period starting in 2006 or 2007. The total amount of money Perez borrowed from the Robainas was $750,000.

Perez needed the money to keep his Ponzi scheme afloat.

The loans, some of which were made in the form of mortgages on Perez properties, stipulated on paper an interest rate of 18 percent. But Perez has reportedly told prosecutors that the actual interest rate was 36 percent – a usury rate that would be illegal.

Perez claimed the mortgage documents and promissory notes were deliberately falsified to cover the illegal transaction. He has also claimed that the illegal portion of the payments were made in cash to Robaina.

Prosecutors were investigating whether Robaina paid taxes on those cash payments.

Perez remains in prison, but his attorney, Alvin Entin told CBS News he was pleased but not surprised by the news.

Entin said Perez helped with the case.

“Hopefully he may get some credit for his cooperation,” Entin said via phone.

Robaina’s wife, Raiza Villacis Robaina, is also accused of being part of the scheme and was also charged with tax evasion.

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The next hearing for the Robaina’s will be June 7 at 10 a.m.