Representative Steve Stockman (R-TX) has sent a formal letter to the National Security Agency asking it to hand over “all its metadata” on the e-mail accounts of a former division director at the Internal Revenue Service.

“Your prompt cooperation in this matter will be greatly appreciated and will help establish how IRS and other personnel violated rights protected by the First Amendment,” Stockman wrote on Friday.

The request came hours after the IRS told a congressional committee that it had “lost” all of the former IRS Exempt Organizations division director’s e-mails between January 2009 and April 2011.

The IRS has been under investigation since 2013, when the tax agency revealed that it selectively targeted political groups applying for tax-exempt status, particularly those with conservative and “Tea Party” leanings and later those with liberal and “Occupy”-related names.

“The fact that I am just learning about this, over a year into the investigation, is completely unacceptable and now calls into question the credibility of the IRS’s response to Congressional inquiries,” said Dave Camp (R-MI), chairman of the Ways and Means Committee, in a statement also on Friday. “There needs to be an immediate investigation and forensic audit by Department of Justice as well as the Inspector General.”

Neither the NSA nor Rep. Stockman’s office immediately responded to Ars’ request for comment.