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For the first time in years, the IRS was knocked down a peg or two.

In a hearing that escalated into a boisterous public shaming of one of the country's most-feared government agencies, lawmakers took turns Friday calling outgoing IRS Commissioner Steven Miller on the carpet for his department's scandalous practice of targeting conservative groups.

Miller rebuffed attempts to extract the names of those responsible, saying he did not know. But lawmakers vowed that the tense hearing would mark only the start of a series of investigations, in which criminal activity could be probed.

Rep. Mike Kelly, R-Pa., seemed to capture the angst against the agency toward the end of the hours-long hearing, as he described the ways its agents are capable of ruining lives.

"You can put anybody out of business that you want. ... When the IRS comes in there, you're not allowed to be shoddy," he said, suggesting the agency's leadership was being held to a different standard now that it is coming under scrutiny.

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"This is absolutely an overreach, and this is an outrage for all Americans," he said.

When he finished, the committee room erupted in cheers and applause that lasted several seconds.

The hearing, though, was more than just venting.

While Democrats voiced concern that the latest scandal would be used to score "political points," lawmakers on both sides of the aisle scolded the agency. And they made clear they'd be pressuring the IRS in the weeks to come on several points -- namely, who was responsible and whether lawmakers were overtly lied to last year.

On the first question, they got few answers from Miller during Friday's testimony.

But they repeatedly confronted the acting commissioner -- who was ousted from him job earlier this week -- about his and other officials' failure to disclose the program last year despite being aware of it.

"In fact, we were repeatedly told no such targeting was happening. That isn't being misled, that's lying," said Rep. Dave Camp, R-Mich., the chairman of the House Ways and Means Committee.

Miller seemed to frustrate lawmakers' attempts to dig deeper. He claimed, a week after the scandal broke and a year after he first learned of the practice, that he still did not know who was responsible.

"I don't have that name," he testified, after Rep. Dave Reichert, R-Wash., asked who was behind the program.

Miller also claimed -- over and over -- he was being honest with Congress during a hearing last year.

"You did not share the information you knew," Reichert charged.

"I answered all questions truthfully," Miller replied.

This claim was met with deep skepticism Friday. Miller acknowledged he learned of the practice during a May 3, 2012, briefing. Yet when he was asked about it at a July 25 hearing that year, he said only that some applications fell into a particular category -- and that those organizations were grouped for "consistency" and "quality."

A letter he wrote to a Republican lawmaker the month before also gave a general description of the process without acknowledging that some groups were being singled out based on words like "Tea Party" and "Patriot."

"How can we not conclude that you misled this committee?" Rep. Paul Ryan, R-Wis., former GOP vice presidential nominee, asked Miller.

Miller said he "did not mislead the committee" and stands by his answer.

Asked whether his answer was "incomplete," he said again he answered "truthfully."

Miller objected to the term "targeting," and claimed political motivations were not at play in the program, which began in 2010. But he apologized for the program and said "foolish mistakes were made by people trying to be more efficient."

"As acting commissioner, I want to apologize on the behalf of the Internal Revenue Service for the mistakes that we made and the poor service provided," Miller said. "The affected organizations and the American public deserve better."

The hearing is the first to examine the scandal, and will likely kick off a string of subsequent hearings and investigations. Republicans made clear that the two retirements or resignations to date would not satisfy their concerns.

Camp ripped the tax-collecting agency over the practice at the start of the hearing. "Now we know the truth -- or at least some of it," he said. "We also know that these revelations are just the tip of the iceberg. It would be a mistake to treat this as just one scandal."

He questioned how high the scandal went, and also suggested there was other targeting of conservatives that has not yet been acknowledged by the agency. He called it part of a "culture of cover-ups."

"This systemic abuse cannot be fixed with just one resignation, or two," he said. He said the problem is not just personnel, but the size and scope of the IRS.

The inspector general who released a scathing report on the agency also testified Friday. J. Russell George -- the Treasury Inspector General for Tax Administration -- said his findings raised "troubling questions" about the agency, while claiming some of the wrongdoing was apparently done with no-to-little supervision.

But he said all three allegations against the agency turned out to be true -- that it was using "inappropriate criteria" to screen conservative groups, it was delaying applications and it was asking unnecessary questions.

Rep. Sander Levin, D-Mich., the top Democrat on the committee, said the agency's management "completely failed the American people." At the same time, he urged Republicans not to use the hearing to "score political points."

Republicans, though, expressed more concern after they learned Thursday that the IRS official who led the tax-exempt organizations unit when the targeting took place -- Sarah Hall Ingram -- has since moved over to the IRS office responsible for ObamaCare.

Miller said Friday he was the one who promoted her and called her a "superb civil servant."

The acknowledgement comes after the administration announced that Ingram's successor Joseph Grant -- who had only been on the job a few days -- would be retiring.

President Obama, meanwhile, maintained Thursday that he didn't know about the investigation into the IRS program until it was made public. Obama also appointed a new acting commissioner -- White House budget officer Daniel Werfel -- after the prior IRS chief announced his resignation.