MIAMI (CBSMiami) – The tax fraud trial against former Hialeah Mayor Julio Robaina began Friday morning.

Robaina and his wife Raiza  are charged with fraud, conspiracy and falsifying documents.

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The two arrived at the Federal courthouse. Minutes later opening statements began.

The 12 member jury and four alternates were introduced to the case by Michael Davis, the prosecutor representing the government.  He began by outlining the evidence in a clear and concise manner on blue monitors inside the courtroom.

The charges are the result of an investigation, first reported by CBS4 News in 2011, stemming 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.

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.

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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 claims 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.

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

The couple is being tried together.

Their attorney David Garvin addressed the jury by saying the Robainas were anxiously awaiting the trial day to come.  He also said the case should no have been tried in federal court but rather a civil audit because the Robaina’s were willing to pay their taxes but the investigation began.

The trial is expected to last anywhere from two  to three weeks.

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U.S. Immigration and Customs Enforcement’s (ICE) Homeland Security Investigations (HSI) worked alongside the Internal Revenue Service’s (IRS) Criminal Investigation Division on their case.

Marybel Rodriguez