As Senate Democrats vowed to keep up the fight over the Judiciary Committee’s leaked memo probe, the central figure in the investigation now says “thousands” of documents from the minority were likely downloaded by an ambitious young GOP staffer.

While some Republicans hoped the ouster of Manuel Miranda, Majority Leader Bill Frist’s (R-Tenn.) top adviser on judicial nominations, could return the focus to charges of Democratic obstruction, Miranda’s resignation letter provided the clearest glimpse yet into how the process unfolded.

Refusing to go away quietly, Miranda vowed to “speak freely” about the memos and their contents, which involved liberal interest groups pushing Democrats to block President Bush’s judicial nominations. “The ones made public are the least indicting of the ones I came to see,” Miranda wrote, following up a complaint he filed Friday with the Ethics Committee charging Judiciary Democrats with “public corruption.”

Without explaining his source, Miranda wrote that he recently learned that “perhaps thousands of documents” from Judiciary Democrats were taken from a jointly shared computer by a younger GOP staffer working on the committee, exponentially more than the original 14 that were published on conservative Web sites in mid-November.

The unnamed staffer, who gave up his legislative staff assistant position and left the committee at the end of last year, read only about 5 percent of those documents, a fraction of which Miranda read himself, according to his resignation letter, a copy of which was given to Roll Call. The staffer apparently wanted to write a book one day about the nomination process, using the flood of memos as a source.

Some Senate Republican strategists hoped to move beyond the entire memo issue and get back to fighting the issue of obstruction and filibusters, believing that the memos only illustrated something that conservatives had long known: Democrats work closely with liberal allies on nomination fights. But the memo probe is likely to continue to dominate the focus of the Judiciary Committee’s work for weeks to come, with Sergeant-at-Arms Bill Pickle not due to finish his investigation until the end of this month.

Pickle is set to update Senators on the committee about the status of his probe Tuesday, but the format is still unclear, and Democrats are pushing for a separate briefing from Republicans.

Even with Miranda pushed out of his job with Frist, Senate Democrats said they still intend to push for a detailed accounting of the memo accessing and whether criminal or internal ethical breaches occurred. One senior Judiciary Democrat, Sen. Dick Durbin (Ill.), said he intends to demand that Pickle examine the flow of where the memos went and whether top White House officials had access to them.

“It will reach beyond the committee,” Durbin predicted. “There are many questions that need to be asked.”

“It’s not enough for me,” Minority Whip Harry Reid (D-Nev.) said of Miranda’s resignation. “Information was stolen. Sensitive writings of members of the Judiciary Committee were stolen. I just don’t think we should let that go. The American public deserves more.”

The handling of the investigation has left Frist and Judiciary Chairman Orrin Hatch (R-Utah) fighting on two fronts, against both Democrats pushing for criminal or ethics charges and conservative activists who came to revere Miranda’s sharp-elbowed approach to the nomination battles.

Frist’s office declined to comment on the entire matter Friday.

In his official complaint to the Ethics Committee, citing memos that he read but have not yet been made public, Miranda alleged there was proof that there were promises of financial political support in the 2002 elections to Democrats who blocked certain judges.

By resigning, Miranda removes the possibility of the Ethics Committee having any role in disciplining him, since the panel has no jurisdiction over former staffers.

Miranda wrote that his reason for quitting the Senate was to free Frist of the political stigma of the investigation. “I have departed so as to not distract the leader from pursuing a needed legislative agenda,” he said.

Miranda and other conservative activists contend that getting the memos was not a criminal or ethical breach, since the former aide and Miranda, who worked at Judiciary in the 107th Congress, have told investigators they took the memos off a computer server shared by Republican and Democratic staff. It’s unclear who gave the memos to media outlets in mid-November, but conservatives say the memos weren’t protected by confidential status.

But Durbin and Reid said they suspect more than two committee staffers were involved, and Durbin is certain to use the notion that “thousands” of documents were taken to bolster his belief that the memos may have gone to “many others.”

“Over a long period of time a substantial number of documents were stolen,” he said.

On Thursday, at Judiciary’s first nomination hearing of the year, Durbin asked a nominee for the 9th U.S. Circuit Court of Appeals, William Meyers, whether he had seen any Democratic staff memos in advance of his hearing. Meyers said he had not. Durbin said he plans to ask that question of every nominee appearing before the committee from now on.

Also, once Pickle presents his report later this month, Durbin said he intends to take the timeline of how long GOP staffers were looking at Democratic memos and then send a letter to every nominee who appeared before the panel during that time asking if they saw or heard about any Democratic strategy memos prior to appearing before the panel.

Durbin has suspicions that nominees might have seen the memos, or that the memos were used by Judiciary Republicans, the Justice Department and the White House Counsel’s office as they prepped nominees for hearings.

Pickle, who has come under fire from conservatives who feel he was too aggressive pursuing Miranda, defended his investigation last week. “There’s no pre-judging,” he said, noting he had a 30-year career in law enforcement that included 26 years in the Secret Service. “I’m just digging out the facts.”

He denied suggestions that he pushed Frist’s office to force Miranda to resign. “I had nothing to do with that,” he said.

And he promised a lengthy report, which would be made public if Hatch and Sen. Patrick Leahy (D-Vt.), the committee’s ranking member, decide to do so.