WASHINGTON (AP) - Federal investigators have told Congress that they have recovered data that may include lost emails from one of the pivotal figures in the controversy over the IRS's treatment of tea party groups, congressional aides said Friday. Frederick Hill, spokesman for Republicans who run the House Oversight and Government Reform Committee, said the investigators told congressional staff at a briefing Friday that they have recovered up to 30,000 emails to and from Lois Lerner. "They didn't indicate any doubt that they'll be able to recover emails," Hill said. A statement from Democrats and Republicans on the Senate Finance Committee was more measured. It said the investigators have recovered data "which may include emails to and/or from Lois Lerner which could be material to the investigation." The Senate Finance statement did not specify a figure. In a statement, the IRS said it remains committed to cooperating with all investigations. Lerner headed the IRS division that processes applications for tax exempt status. She told a congressional committee that she'd done nothing wrong and refused to answer lawmakers' questions, citing her constitutional protection against self-incrimination, and has since retired. Congressional Republicans have been trying to determine whether the treatment of conservative groups was politically motivated. The IRS has acknowledged that its handling of those groups was inappropriately burdensome, but no evidence has been made public that anyone outside the IRS directed the targeting or knew about it. The investigators were from the Treasury Inspector General for Tax Administration, which audits the IRS. A spokeswoman for the inspector general, Karen Kraushaar, declined comment, saying the investigation was continuing. In May 2013, the investigators issued a report saying IRS agents had given exceptionally close scrutiny to tea party and other conservative groups that applied for tax-exempt status. Since then, documents have suggested that liberal groups were also targeted for examinations, though Republicans say conservative organizations were treated more harshly. IRS officials have said Lerner's computer crashed in 2011, destroying an untold number of emails. Hill said it will take weeks for the investigators to process the information into a usable format and give it to the IRS, which would review it. The House Oversight panel is headed by Rep. Darrell Issa, R-Calif. The Senate Finance Committee aides said the investigators must assess if the data can be made readable before documents can be delivered to their committee. They said their panel expects to complete its bipartisan investigation of the IRS early next year. By then, majority control of the committee will flip from Democrats to Republicans.