"Are you going to look at the fact that the head of the agency that targeted conservative groups knew in April and didn't tell us and didn't tell you?" until June, he said.
Cole, who said the Justice Department didn't learn about the email loss until after it was reported in the news media, wouldn't commit to investigating the two-month lag but said it could be an area of interest if there is reason to think a crime had occurred.
Lerner, who refused to answer questions at two House committee hearings, has become a central figure in several congressional investigations into the handling of applications for tax-exempt status by tea party groups. At both hearings, Lerner cited her Fifth Amendment right not to incriminate herself. In May, the Republican-led House voted to hold Lerner in contempt of Congress for refusing to testify.
The IRS revealed last month that it lost the emails in 2011 when Lerner's computer crashed. IRS Commissioner John Koskinen has said he's seen no evidence that anyone committed a crime in connection with the lost emails. There is no evidence that Lerner intentionally destroyed them, he said, adding that IRS has gone to great lengths trying to retrieve lost documents on her computer.
Lerner's attorney, William Taylor III, declined to comment.
Koskinen said he first learned there was a problem with Lerner's computer in February, but he didn't learn that emails were lost until April. The IRS notified Congress on June 13, and Koskinen testified that he wanted to learn the scope of the problem before telling Congress. For example, he said, technicians were able to locate 24,000 Lerner emails on other IRS employees' computers.
The disclosure by Lerner in May 2013 that the IRS had engaged in "inappropriate" targeting of conservatives set off a political firestorm that continues to flare in this election year. Word that investigators are broadening their inquiry to include the missing emails comes as Republican lawmakers accuse the Obama administration of not cooperating with their investigation and failing to take the matter seriously enough. Attorney General Eric Holder has resisted their calls to appoint a special prosecutor.
"Crimes were committed. Regulations were violated. Rules were broken. And Americans' constitutional rights were violated by Lois Lerner and perhaps others around her," Rep. Darrell Issa, R-Calif., a leading Justice Department critic told Cole.
Cole said the investigation remains active but would not answer specific questions about its status.