Lost emails from a former IRS official will again take center stage on Capitol Hill this week.

It comes as House Republicans continue to dig into the year-old controversy surrounding claims that the agency unfairly targeted conservative groups applying for tax exempt status. Earlier this month, the IRS told lawmakers two years worth of emails from former official Lois Lerner had been lost due to a hard drive crash.

At a hearing about the issue Friday, Republican Paul Ryan blasted IRS Commissioner John Koskinen, suggesting the agency had intentionally misled congressional investigators. The agency denies any wrongdoing, and says it has made an unprecedented effort to produce documents related to the investigation.

Koskinen will appear before the House Committee on Oversight and Government Reform Monday evening at 7 p.m. to discuss the loss of Lerner's emails. Former IRS attorney and current White House counsel Jennifer O'Connor will appear before the same committee Tuesday morning.