A West Islip businessman pleaded not guilty Thursday to charges of mortgage fraud, which prosecutors say amounted to $2.5 million.

Louis LaDonna, 39, is accused of procuring straw buyers with fake documentation to get no-down payment mortgages. His attorney, William Keahon, says he?s confident his client will be cleared of the 13 charges.

Meanwhile, Suffolk County District Attorney Thomas Spota says mortgage fraud is becoming increasingly common in the county. So far, he says investigators have uncovered $9 million in fraudulent mortgages and equity thefts. Twenty-seven people have been arrested since June, when Spota added a mortgage fraud unit to the department.

"What we're seeing in Suffolk County is an explosion of fraud involving ... every facet of the mortgage process, from applicants to the mortgage brokers to bank employees to appraisers," Spota said.

According to Spota, 30 mortgage fraud investigations are currently under way in the county.