A misplaced paycheck stub started it all. Gary Foster, a former assistant vice president in Citigroup’s internal treasury finance department, said the stub — left next to an office printer — showed that a subordinate made $10,000 more than him.

“I was shocked,” Foster said during an interview with John Gill, J.D., CFE, ACFE vice president – education, at the Wednesday closing General Session. “I was in love with the company. I felt completely devastated. I’m working like crazy. … I felt betrayed.”

During the next two years, Foster’s resentment against Citibank festered. Finally, he realized that he needed some payback for what he deserved.