The aide, whose name was not reported, said the panel was examining a statement Holder made during an exchange with U.S. Rep. Hank Johnson, D-Ga., about whether the department could prosecute reporters under the 1917 Espionage Act, The Hill reported Tuesday.
"In regard to potential prosecution of the press for the disclosure of material, this is not something I've ever been involved in, heard of, or would think would be wise policy," Holder said under oath during the May 15 hearing.
A week after the hearing, NBC News reported Holder personally authorized a search warrant that called Fox News Chief Washington Correspondent James Rosen a co-conspirator in a national security leaks case.
The Judiciary Committee is investigating whether the report is contrary to Holder's claim he didn't look into or was involved in possible prosecution of media outlets in a leaks case.
White House press secretary Jay Carney told reporters Wednesday he sees "no conflict between what [Holder] said and the published reports."
Carney was asked whether Holder's testimony -- that he has never been involved in "potential prosecution of the press for the disclosure of material" -- conflicted with a report that he personally authorized the Rosen search warrant. He said questioners "are conflating the subpoena with prosecution."
"I think every published report -- I think the Attorney General talked about prosecution," Carney said. "Every published report that I've read about the case in question says that it's completed, no further charges or prosecution is contemplated. "
The May 15 Judiciary hearing was convened after The Associated Press revealed the Justice Department subpoenaed phone records in a different investigation into leaks.
Justice officials didn't respond to a request for comment, The Hill said.
Johnson defended Holder, saying the attorney general's comment was specific to Johnson's questioning about the Espionage Act, not other investigations.
"The attorney general's statement that no journalists have been prosecuted under the Espionage Act during his tenure is accurate," he told The Hill.
Rep. James Sensenbrenner Jr., R-Wis., the second-ranking Judiciary Committee Republican, accused Holder of misleading the committee when he claimed to not know about the AP investigation, and during the investigation of Operation Fast and Furious gun-walking operation.
Sensenbrenner told The Hill Holder should resign.
"As we saw in Fast and Furious and are seeing now, Attorney General Holder refuses to hold himself accountable," Sensenbrenner said. "The head of DOJ should be someone the American people can trust. Attorney General Holder should resign."
President Barack Obama said he was "troubled" by reports about the department's surveillance of reporters. He ordered Holder to review the Justice Department's guidelines concerning investigations involving reporters. The findings are due July 12.