The Justice Department said Thursday it is investigating whether resigning Attorney General Alberto Gonzales lied or otherwise misled Congress last month in sworn testimony about the Bush administration's terrorist surveillance program.

The inquiry, confirmed by Justice Department Inspector General Glenn A. Fine, comes three days after Gonzales abruptly announced he was stepping down despite months of vowing he would remain on the job.

In a letter to Senate Judiciary Chairman Patrick Leahy, who two weeks ago asked for the inquiry, Fine said his investigators believe they "will be able to assess most of the issues that you raise in your letter."

Leahy had also asked Fine to look into whether Gonzales gave inaccurate testimony about the firings of several U.S. attorneys last year.

"You identified five issues and asked that we investigate whether the statements made by the attorney general were intentionally false, misleading, or inappropriate," Fine wrote in his four-paragraph response to Leahy in the letter dated Thursday.

"The OIG has ongoing investigations that relate to most of the subjects addressed by the attorney general's testimony that you identified," Fine told Leahy.