Ngozi Pole, Kennedy's former office manager, was convicted on all five counts of wire fraud and a single count of theft of government property.
Each wire fraud charge carries a maximum prison sentence of 20 years and a $250,000 fine. The theft of government property charge has a maximum prison sentence of 10 years and a $250,000 fine. Sentencing is set for July 14.
As office manager, Pole, of Waldorf, Md., was responsible for sending staff salary and bonus information to the Senate Disbursing Office. Prosecutors said during the trial that Pole submitted false paperwork for unauthorized pay and bonuses from 2003 to 2007. Only Kennedy or his chief of staff were authorized to approve salary and bonus payments.
Pole covered up the excess payments he made to himself by providing false documentation to Kennedy's chief of staff, prosecutors said during the trial.
"He knew he held the keys to the budget and he could do what he wanted without anyone being the wiser," prosecutor Ethan Levisohn said during closing arguments.
Pole was paid nearly $90,000 in authorized salary and bonuses in fiscal year 2006, prosecutors said.
"But that wasn't enough for him," said prosecutor Deborah Mayer. "He wanted more. So he took more."
The trial shed light on some of the inner workings of Kennedy's office, which for decades was one of the busiest and most powerful in the Senate.
Pole testified that he handled payroll, bonus and other budgetary matters for the office with little or no guidance from his superiors, who he said were too busy focusing on other matters.
"I was forced to do a lot of guessing to get my job done," said Pole.
He said the marching orders in Kennedy's high-pressure, fast-paced office were simple: get things done.
It was standard practice to "spend down" any surplus in Kennedy's annual office budget to a zero balance at the end of each fiscal year, Pole said.
Pole said the excess payments he made to himself were part of his efforts to "spend down" surplus funds. He also gave "spend down" bonuses to some other staffers and bought additional office equipment as part of that effort, without approval from his bosses.
Prosecutors, however, said Pole received lists from his bosses showing which staffers were approved for bonuses and the amounts.
Kennedy usually paid staffers holiday bonuses around Christmas that generally ranged from $1,000 to $2,000 per employee, prosecutors said. Staffers also got bonuses at the end of the fiscal year ranging from $3,000 to $5,000.