There is always a risk for defendants who take the stand in their own defense that prosecutors will land some shots during cross-examination.

Annette Bongiorno, a longtime aide for Bernard L. Madoff, rolled the dice this week in Manhattan federal court and went toe to toe with the government.

During her three days on the witness stand, Ms. Bongiorno portrayed herself as a hapless straphanger in Mr. Madoff's fraud, totally ignorant of the massive Ponzi scheme taking place at her employer of 40 years.

Ms. Bongiorno testified she had no formal investment training, saying Thursday she didn't know what the Standard & Poor's 500 was or even what a Treasury bond is, despite decades in the securities industry.

She relied entirely on the instructions of "Bernie" and never questioned him, Ms. Bongiorno said.