IRS commissioner hits back

• IRS chief testifies following revelations the agency lost thousands of emails


• "I don't believe you," Rep. Paul Ryan told John Koskinen at a hearing


• "I didn't come out of retirement to play games," Koskinen said afterward


• Koskinen has a reputation for honesty, toughness, but is also unflappable

Washington (CNN) -- Congressional Republicans pummeled him with questions and accusations, all but accusing him of perjury. But John Koskinen just didn't sit there and take it. The IRS commissioner hit back.

This all has unfolded over the past several days with Koskinen enduring two grueling appearances before House committees led by Republicans, who have been aggressively pursuing the controversy over IRS targeting of conservative groups.

"I didn't come out of retirement to play games," Koskinen told reporters after Monday night's marathon hearing before the House Oversight Committee. "I came out of retirement to restore the credibility of the IRS."

He's new to the top job since the targeting revelations rocked the agency last year, and triggered congressional inquiries.

But Koskinen, 74, a government veteran, is taking the brunt of congressional pressure now after the agency admitted it lost thousands of emails wanted by lawmakers investigating the scandal.

Rep. Paul Ryan flat out questioned whether he was being truthful with Congress, and Darrell Issa, the Oversight chairman, called him out for being evasive.

"All the emails we have will be provided. I did not say I would provide you emails that disappeared. If you have a magical way for me to do that, I'd be happy to know about it," he said.

That answer raised eyebrows in an environment where committee chairman are rarely crossed.

Mixing it up

But it looks like Koskinen likes to mix it up, and from all appearances, it looks as if he likes to take the field when the chips are down.

Firm, direct and experienced. That about sums up the no nonsense former corporate executive who also held top positions in government and is a big league Democratic political donor. He also doesn't really need a job. Financial disclosure papers show his personal wealth may be as high as $27 million.

The White House described him as a "retired corporate restructuring expert" before President Barack Obama nominated him to the post last summer.

"John is an expert at turning around institutions in need of reform," Obama said at the time. "I am confident that John will do whatever it takes to restore the public's trust in the agency."

Koskinen went to Duke undergrad and Yale Law School before clerking for a federal judge. He has political chops, too. having worked for a New York mayor, a senator, and was once deputy mayor of Washington during a financial crisis.

He had a critical role in preparing for Y-2-K, and headed mortgage giant Freddie Mac when its troubles were spinning out of control. He also helped manage two government shutdowns in 1995 when he worked in Clinton's White House budget office.

Larry Hirsch, a former Freddie Mac board member, told CBS that Koskinen boosted morale as the agency struggled to survive.

"Obviously after the financial crisis, the company was in internal and external crisis," Hirsch said after Obama nominated Koskinen for the IRS job. "John walked in and immediately handled what was happening with the company. He had the quiet strength and openness to take a very depressed management team and employee group to give them the confidence they were valued and the company had a future."

'Unflappable' and 'honest'

Koskinen also served on the board of trustees at Duke University from 1985 to 1998 and chaired the board's business and finance committee during the tenure of then-University President Keith Brodie.

Brodie, who is also a psychiatry professor, said he spent a lot of time working with Koskinen during difficult financial times at the university and called Koskinen "remarkably talented."

And although congressional Republicans are questioning his integrity, Brodie said Koskinen was a "very, very honest guy" and steady.

"He was quite unflappable back then and really a joy to work with," Brodie said.

Beating back accusations

While Koskinen could plunge a Duke University boardroom into a deferential silence, Congress is a very different animal.

By the end of his question time on Monday, a dissatisfied Issa proclaimed: "I've lost my patience with you."

Common sense! Instead of the criminal code you want to rely on common sense?

- Rep. Trey Gowdy, R-South Carolina

But Koskinen kept his cool.

Rep. Michael Turner, a Ohio Republican, tried to push Koskinen to say whether a crime had been committed amid the IRS scandal.

Turner pushed back after Koskinen said he had not seen any evidence of a crime or any evidence for any number of other things relating to the lost emails belonging to former top IRS official Lois Lerner.

"We have no evidence whether she (Lerner) beat her dog, whether she beat children," Koskinen said.

I reject the suggestion that my integrity depends on my calling the FBI

- IRS Commissionner John Koskinen

But then Turner questioned Koskinen's integrity when he said he would not call the FBI to investigate the agency.

"I reject the suggestion that my integrity depends on my calling the FBI," Koskinen said, and later said there were "no facts" behind Turner's criminal accusations.

He later said he hadn't seen any evidence of "wrongdoing" in the loss of Lerner's emails, triggering more Republican incredulity.