WASHINGTON — At the center of a political storm, an Internal Revenue Service supervisor whose agents targeted conservative groups swore Wednesday that she did nothing wrong, broke no laws and never lied to Congress. Then she refused to answer lawmakers’ further questions, citing her Fifth Amendment right not to incriminate herself.

In one of the most electric moments since the IRS controversy erupted nearly two weeks ago, Lois Lerner unwaveringly defended herself before the House Oversight and Government Reform Committee. But she would say no more, citing legal advice in the face of a federal investigation.

Members of Congress have angrily complained that Lerner and other high-ranking IRS officials did not inform them that conservative groups were singled out, even though lawmakers repeatedly asked the IRS about it after hearing complaints from local tea party groups.

The Justice Department has launched a criminal probe of the murky events over the 2010 and 2012 election campaigns, saying it is looking into potential civil rights violations. Top IRS officials said Lerner didn’t tell them for nearly a year after she learned that agents working under her had improperly singled out conservative groups for additional scrutiny when they applied for tax-exempt status.

Under unrelenting criticism, most forcefully from Republicans but also from Democrats and people outside politics, administration officials from President Barack Obama on down have denounced the targeting as inappropriate and inexcusable.

Lerner, who heads the IRS division that handles applications for tax-exempt status and who first disclosed the targeting at a legal conference, has said the same. But she also spoke up for herself Wednesday, sitting stern-faced at the committee witness table.

“I have not done anything wrong,” she said. “I have not broken any laws, I have not violated any IRS rules or regulations, and I have not provided false information to this or any other congressional committee.”

By one lawmaker’s count, Lerner was asked 14 times by members of Congress or their staffs without revealing that the groups had been targeted. On Wednesday, lawmakers didn’t get a chance to ask Lerner again.

Nine minutes after she began speaking, Lerner was excused, though committee Chairman Darrell Issa, R-Calif., said he might recall her. Issa said Lerner may have forfeited her Fifth Amendment privilege not to testify by giving an opening statement, but several law professors were skeptical that Issa could make that stick.

The hearing was Congress’ third on the controversy in the past week. Taken together, testimony by current and former officials indicates that Lerner’s actions were consistent with theirs: Once officials learned that conservative groups were being targeted, they say they made sure the practice was stopped.