The Justice Department is investigating U.S. Attorney General Alberto Gonzales’s meeting with a former top aide about the controversial firing of federal prosecutors last year, according to a letter released on Thursday by the Senate Judiciary committee.

In testimony before the House Judiciary committee, the former aide, Monica Goodling, said Gonzales told her about his recollections of the dismissals in March, shortly before she resigned.

Gonzales, in earlier testimony before the committee, said he had not gone back to talk to staff involved in the firings “in order to protect the integrity” of the investigations.

Senate Judiciary committee Chairman Patrick Leahy and Pennsylvania Sen. Arlen Specter, the panel’s senior Republican, last week asked Justice Department investigators whether an internal probe includes the meeting Goodling testified about.

The Justice Department’s Office of Inspector General (OIG) and Office of Professional Responsibility (OPR) confirmed in a letter to the Senate panel that their joint investigation “does include this matter.”

A Justice Department spokesman could not be immediately reached for comment.

President George W. Bush and Gonzales say the firing of nine of the 93 U.S. attorneys, all Bush appointees, was justified though mishandled.

Critics have questioned whether partisan politics played an improper role in the dismissal plans, which originated at the White House. One of the fired prosecutors was replaced by a former aide to White House political adviser Karl Rove.

The Justice Department’s internal investigation was already looking into whether Goodling brought political questions into the hiring process for career positions, such as assistant U.S. attorneys. That would violate federal law.

Leahy said he hoped the White House would not shut down the Justice Department investigation.

“This internal investigation is an important step in getting to the truth behind this matter, and they should be allowed to do their jobs without interference from this administration,” Leahy said in a statement.

Goodling, who served as a senior counsel to Gonzales, testified last month after receiving immunity from prosecution and told Congress that political considerations were often involved in hiring.

Democratic lawmakers on Wednesday issued subpoenas to former White House counsel Harriet Miers and political director Sara Taylor to testify in the ongoing inquiry into the dismissals of federal prosecutors.