The head of the Internal Revenue Service division that targeted conservative groups told a congressional committee Wednesday that she did nothing wrong and is not to blame for the wrongdoing, but then invoked her Fifth Amendment protections against self-incrimination and refused to answer lawmakers' questions.

Lois Lerner was a witness lawmakers hoped would help finally answer the fundamental questions about who authorized the IRS to target the Tea Party and other conservative groups opposed to President Obama ahead of last year's election.

House Oversight and Government Reform Committee Chairman Darrell Issa, R-Calif., dismissed Lerner from the hearing after she invoked the Fifth Amendment. He said he may recall Lerner to testify at a future hearing, saying she may have waived her Fifth Amendment rights when she first delivered an opening statement proclaiming her innocence. To force Lerner to return and testify, Issa refused to adjourn the hearing at the end of the day, instead gaveling it into recess.

"I am looking into the possibility of recalling her," Issa said.

In her opening statement, Lerner said her decision not to answer questions should not be interpreted as an indication that she is guilty of anything.

"I have not done anything wrong," Lerner said, reading from a sheet of paper at the start of the hearing. "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."

Lerner, who appeared under subpoena, sat at a table with former IRS chief Doug Schulman, Deputy Treasury Secretary Neil Wolin and J. Russell George, the Treasury Inspector General. George issued a report earlier this month revealing that Lerner's division had issued a "Be On the Look Out" order for conservative groups seeking tax-exempt status, particularly those with names that included "Tea Party," "Patriot" and other words suggesting applicants might be right-leaning.

As the oversight committee grilled IRS officials, the House Financial Services Committee pressed Treasury Secretary Jacob Lew in a separate hearing about when he learned of the IRS targeting scheme.

Lew, before taking the helm at Treasury, served as Obama's chief of staff in 2012. He told the panel he first learned that the IRS was being investigated in mid-March, but did not know the details of the targeting until the audit was released last week.

That answer did not satisfy Rep. Sean Duffy, R-Wis., who repeatedly pressed Lew on when he knew the IRS was singling out conservatives for inappropriate scrutiny.

"You're dodging me because the bottom line is you knew before the [inspector general's] report came out that the IRS was targeting Americans," Duffy told Lew.

Lawmakers, particularly Republicans, have been trying to determine whether IRS and Treasury officials alerted the White House to the targeting of conservatives in the months ahead of the contentious 2012 election.

Rep. Jim Jordan, R-Ohio, noted that Shulman, the former IRS chief, had been to the White House more than 100 times between 2010 and 2011 when the investigation was underway.

Schulman said he couldn't remember the purpose of the visits but insisted he never discussed the IRS investigation with anyone in the White House.