April 16, 2007  -- Attorney General Alberto Gonzales' assertion that he was not involved in identifying the eight U.S. attorneys who were asked to resign last year is at odds with a recently released internal Department of Justice e-mail, ABC News has learned.

That e-mail said that Gonzales supported firing one federal prosecutor six months before she was asked to leave.

Gonzales was scheduled to testify before the Senate Judiciary Committee Tuesday, but his testimony was postponed until Thursday because of the shooting rampage at Virginia Tech University.

When Gonzales appears before the committee, a central focus will be the extent of his involvement in the firings.

Gonzales has insisted he left those decisions to his staff, but ABC News has learned he was so concerned about U.S. attorney Carol Lam's lackluster record on immigration enforcement in San Diego that he supported firing her months before she was dismissed, according to a newly released e-mail from his former chief of staff.

The e-mail, which came from Gonzales aide Kyle Sampson, appeared to contradict the prepared written testimony Gonzales submitted to Congress over the weekend in advance of his Senate Judiciary Committee hearing Tuesday. In his prepared testimony, Gonzales said that during the months that his senior staff was evaluating U.S. attorneys, including Lam, "I did not make the decisions about who should or should not be asked to resign."

But the recently released e-mail from Sampson, dated June 1, 2006, indicated that Gonzales was actively involved in discussions about Lam and had decided to fire her if she did not improve. In the e-mail to other top Justice Department officials, Sampson outlined several steps that Gonzales suggested, culminating in Lam's replacement if she failed to bolster immigration enforcement.

"AG [Attorney General] has given additional thought to the San Diego situation and now believes that we should adopt a plan" that would lead to her removal if she "balks" at immigration reform, Sampson wrote.

The e-mail laid out other possible ways to deal with Lam short of dismissal. Gonzales supported the idea of first having "a heart to heart with Lam about the urgent need to improve immigration enforcement" and of working with her "to develop a plan for addressing the problem." Sampson said another alternative would be to "put her on a very short leash.

"If she balks on any of the foregoing or otherwise does not perform in a measurable way … remove her," Sampson wrote of Gonzales' suggested plan. "AG then appoints new U.S. [attorney] from outside the office."

The Lam situation gets to the heart of the U.S. attorney controversy and the focus of the upcoming Gonzales hearing. Senators want to know why the eight prosecutors were fired. Were they fired for cause? Was their performance at issue? Or were their political motives?

Regarding Lam's dismissal, the e-mails show that Sampson asked Justice Department officials William Mercer and Michael Elston for help in presenting a formal plan for Gonzales to approve.

Justice Department official William W. Mercer told congressional investigators on April 11 that he attended a meeting with the attorney general days later to discuss Lam's situation, according to congressional sources. During the meeting, Mercer told Gonzales he was "very concerned" with the problems regarding Lam.

In an e-mail released in the recent document dump from Capitol Hill, Mercer's calendar includes a notation for a 3 p.m. meeting on June 5 -- four days after Sampson's e-mail -- with the attorney general, Sampson, Mercer and Jeff Taylor. The subject of the meeting is listed as "Immigration Enforcement/San Diego USAO [U.S. attorney's office]."

Interestingly, in an e-mail six months earlier, Sampson listed Taylor, who was then a top aide to Gonzales, as a possible replacement for Lam's seat. Taylor was later appointed U.S. attorney in Washington.