Washington (CNN) The IRS watchdog investigating the disappearance of Lois Lerner's emails told a congressional panel on Thursday night they are looking into the possibility of criminal activity.

Lerner was the IRS official at the center of allegations that the Internal Revenue Service targeted tea party groups applying for nonprofit status. Congress requested Lerner's emails from the IRS and agency officials told lawmakers an unknown number of emails had been lost when Lerner's computer crashed.

The Treasury Inspector General for Tax Administration has since recovered a number of those emails.

"There is potential criminal activity," Treasury Deputy Inspector General Timothy Camus told the House Oversight Committee Thursday.

Read More