Vondra's passion eventually carried him to law school to learn more about the law and how to work with attorneys. He now has a C.P.A., a J.D., and has been certified to examine fraud by the A.C.F.E. At PricewaterhouseCoopers, he is the partner in charge of Advisory Services, which specializes in dispute analysis and investigation.

In today's world, Vondra says, "[fraud detection is] really on the radar screen of every single public company in the United States. Accounting has moved from the back page of the Wall Street Journal to the front page."

Most investigations begin with a tip from a whistleblower or a suspicion of some sort, which prompts the audit committee of a company's board of directors to call in Vondra and his group. They'll begin with high-level interviews and then move on to requesting and examining emails—sometimes as many as one million. He and his team run the emails through programs that search for words and phrases like "illegal," "earnings management," and "manipulate." The programs will call up email strings, which may point the auditors to certain accounting files, which can then be pulled up and scrutinized.

In the course of his work, Vondra has served as an expert witness in court cases more than 70 times, and has been hired by the S.E.C. in civil cases to explain accounting fraud in terms a jury can understand.

Vondra can't release the names of cases he's worked on. But he says the Department of Justice recently hired him after they uncovered a Ponzi scheme being conducted by a former state governor, who was running as much as $1 billion through his personal bank account; the department hired Vondra to figure out how he did it. Vondra has also led 70-person teams in some of the highest-profile accounting scandals in recent years, and helped prosecute several top executives.

"It's way more than about numbers," Vondra says of his job. "I'm a C.P.A.; I'm also a lawyer, and a certified fraud examiner—my job entails all these skills."