The IRS revealed to a federal court late Monday that Lois Lerner used a second personal email account registered under a phony name to conduct government business during her time as head of the division that oversees tax-exempt organizations.

IRS lawyer Geoffrey J. Klimas told the court that the agency discovered Lerner had used a second personal email address set up under the name "Toby Miles," reportedly her dog's name. Lerner also used an official agency email address as well as a separate personal one that was previously identified, reported The Washington Times.

The admission came in response to an open-records lawsuit filed by Judicial Watch, a conservative government watchdog group seeking emails related to Lerner's targeting of conservative groups that had filed for tax-exempt status.

The IRS has so far insisted that all of Lerner's official IRS emails were permanently lost when her computer crashed and hard drive was destroyed in 2011, according to Breitbart. Then, in March 2014, as many as 24,000 emails were lost when 422 backup tapes were "magnetically erased," months after the IRS was told to preserve documents, as HNGN reported. Copies of some of her emails were eventually turned over to U.S. House investigators.

Klimas told the court that as the agency was putting together documents to hand over to Judicial Watch, attorneys discovered the additional email account.

"In the process of preparing this status report and for the August 24, 2015, release of Lerner communications, the undersigned attorneys learned that, in addition to emails to or from an email account denominated 'Lois G. Lerner' or 'Lois Home,' some emails responsive to Judicial Watch's request may have been sent to or received from a personal email account denominated 'Toby Miles,'" Klimas told U.S. District Judge Emmet Sullivan, according to Fox News.

Klimas said that in light of the new discovery, the IRS is now reviewing previous releases given to Judicial Watch and will know by the end of August if additional searches need to be done or whether any documents need to be re-released with different redactions.

Judicial Watch President Tom Fitton said he was shocked that the IRS is just now admitting the existence of yet another email address.

"It is simply astonishing that years after this scandal erupted we are learning about an account Lois Lerner used that evidently hadn't been searched," he said, according to The Washington Times.

"This is the latest in a parade of obstruction from the IRS and the Department of Justice on these issues," Fitton told Fox, adding that it is "disturbing" that sensitive government information was on a non-approved private email account.

"This is just another example from the Obama administration of the -- to use an old Nixonian phrase -- modified limited hangout," Fitton said. "The Obama IRS scandal is not over."