The head of the United Nations' in-house investigation into the Oil-for-Food (search) scandal says it could lead to criminal prosecution in the U.S.

Paul Volcker (search) told FOX News that he believes his investigation could uncover evidence that will be turned over to Justice Department prosecutors now weighing possible criminal cases.

In an exclusive interview, Volcker said he's getting the cooperation of people across the globe as he delves into how the United Nations let Saddam Hussein (search) get away with illegally turning the Oil-for-Food program into his own personal multibillion-dollar piggybank. Saddam allegedly stole an estimated $21 billion from the U.N. program and from oil smuggling.

Volcker is also investigating allegations that a high-ranking U.N. official was bribed by Saddam. Congress this week has held two hearings probing the scandal-ridden program.

Volcker defended his decision not to provide 55 U.N. audits of Oil-for-Food, or let U.N. officials testify at Senate Oil-for-Food hearings, saying that doing so now could hurt his own investigation. But he vowed everything will become public when he issues his final report next year.

The Senate Subcommittee on Investigations wants to question Benon Sevan (search), the former head of the program, who has been accused of — but denies — receiving $1 million in bribes while running Oil-for-Food. Volcker said his team will take on Sevan, as well.

"We will find all the evidence we can," he said. "With respect to Mr. Sevan, we will confront him and whatever it is we have. We'll see what he says and we'll reach our own conclusions."

Volcker also seemed surprised at the extent of the scandal.

"I don't like the fact that the accusations are made in the first place," Volcker said. "I don't like to think that this organization [is] that challenged, but the fact is it is."

He said a priority of his investigation is to examine what went wrong in the U.N. bureaucracy that allowed the scandal to occur in the first place.

"Our first priority is to look inside the U.N. and look at their management of the program, look at the allegations of corruption inside the U.N. and report the facts to the American people and to people all over," the former Federal Reserve chairman said.

Some critics express doubt about Volcker's task, noting that his investigators don't even have subpoena power and his panel is funded by the very organization he is investigating.

But Volcker insists he has everything at his disposal and has the tools and independence to get the job done.

FOX News' Eric Shawn contributed to this report.