Congress has more questions about lost emails at the IRS, and the systems that should keep critical federal data backed up.

The House Committee on Oversight and Government Reform met Tuesday morning for another round of back and fort, discussing two years of missing emails from former IRS official Lois Lerner. The agency says the emails were lost as a result of a computer crash, which it became aware of in April.

Republicans say the details are fishy, and want to know if it's part of an attempt to cover up IRS misconduct and claims it unfairly targeted conservative groups applying for tax exempt status in 2013.

"I believe that this investigation is on the right track," said Rep. Cynthia Lummins, R-Wyo. "It's perfectly legitimate."

The committee grilled former IRS attorney and current White House counsel Jennifer O'Connor, who played a key role in producing agency documents for congressional investigators last year. O'Connor told the panel her team worked to produce emails and other documents as quickly as possible, using a collection of specific search terms to help speed up the search. She told lawmakers she was not aware of any attempts to not to store email records.

United States Archivist David Ferriero also testified Tuesday, saying the IRS failed to notify the National Archives of Lerner's lost emails, a requirement under the Federal Records Act.

"Can we safely assume that they broke the law?," Rep. Tim Walberg, R-Mich., asked Ferriero during the hearing.

"They did not follow the law," Ferriero replied.

Democrats say the lost emails are not part of a conspiracy, but rather more indicative of a deeper problem: that the government's computer and backup systems are way out of date. The IRS and other agencies, for example, are still using the Windows XP operating system - originally released in 2001. Despite its popularity, Windows XP is no longer supported by Microsoft.

"If there is one agency that we want to have comprehensive backup, it would be the IRS, is that correct?" Rep. Jackie Speier, D-Calif., asked Ferriero.

"I agree," Ferriero said, "but I also can testify that this issue about updated technology exists in many agencies across the government."

A bill - H.R. 1234 - introduced last year by the committee's ranking Democrat, Maryland Rep. Elijah Cummings, would create new regulations to help back up electronic messages. Republicans and Democrats on the panel said Tuesday they would work together on that legislation, which is estimated to cost around $15 million to implement.