Daniel Bonventre, former back-office director for Bernard L. Madoff Investment Securities LLC, exits Manhattan Federal Courthouse in the Manhattan Borough of New York February 24, 2014. Madoff's former associates are on trial, charged with profiting from the massive $65 billion Ponzi scheme. [Photo/Agencies]

Like Bonventre before her, Bongiorno said Madoff was exceptionally generous with his employees, paying for her honeymoon as a wedding gift. When her mother had a debilitating stroke, Madoff secured her a spot in a nursing home where she had been turned down, she testified, her voice cracking.

"He said, in typical Bernard Madoff fashion, 'I made them an offer they couldn't refuse,'" she recalled.

When she learned of the fraud upon Madoff's arrest in December 2008, she said, she told a colleague to throw the "hero" photo of Madoff away.

The decision to testify in her own defense is unusual for a criminal defendant and represents a calculated risk, offering the jury an explanation but subjecting her to what will likely be intense questioning from the government about how she could have been so completely in the dark.

Prosecutors have not yet had a chance to question Bongiorno, who will resume testifying on Tuesday. The trial, now in its fifth month, is expected to conclude within two weeks.

The case is USA v. O'Hara et al, U.S. District Court, Southern District of New York, No. 10-cr-0228.