As fallout from the City Council slush fund scam widens and threatens to damage the political career of Speaker Christine Quinn, a key figure in the budget scandal has vanished from the scene: Gifford Miller, the former speaker of the council.

Although council documents show that phantom groups first appeared in the final budget of Mr. Miller’s predecessor, the unusual and possibly illegal accounting maneuver grew by leaps and bounds under Mr. Miller, with nearly $10 million parked behind fake organizations during his four-year term as speaker.

In 2002, Mr. Miller’s first year as speaker, more than three times as much money was stashed behind fake groups compared with the sum set aside under the previous speaker, Peter Vallone Sr., council documents show.

Phantom organizations with names such as Magic Mountain Fund, Swan’s Way, and Hicks Decomposition held some $3.8 million in Mr. Miller’s first budget.

The next year, the names grew more sophisticated, as if deliberately designed better to mirror the titles of legitimate organizations that receive funding each year from the City Council.

In that budget, and those that followed, money was set aside for the American Association of Concerned Veterans, the Coalition of Informed Individuals, the Association of Community Partners, the Coalition for Strong Special Education, and the New York Foundation for Community Development, all fictitious organizations.

Mr. Miller has not returned calls for comment and has repeatedly declined to weigh in on the investigation and the budget practice, while bulk of the fallout has landed squarely on Ms. Quinn.

“This issue has received extensive coverage in the media and I really have nothing to add,” Mr. Miller said in an e-mail to The New York Sun.

Using public funds, Ms. Quinn has hired a criminal defense lawyer to represent her during the investigation into the council budget by the U.S. attorney and the Department of Investigation, and she has hired the law firm of Sullivan & Cromwell to represent the council as a whole.

Lawyers say that intentionally inserting false information into an official document, such as the city’s budget, violates a state law against filing a “false instrument,” which sometimes counts as a felony.

Ms. Quinn’s aides have emphasized that the budget mess is one she inherited when she became speaker.

A political consultant, Hank Sheinkopf, said that because Mr. Miller is no longer a public official he’s under no obligation to speak about the investigation and the council’s budget.

“Why insert yourself into a situation when no one thinks you are alive?” he said. “If you want any kind of future in political life, the further you can run from this, the better off you are.”

Since he was forced from his council seat in 2006 because of term limits, Mr. Miller, who was first elected to represent the Upper East Side in 1996 at the age of 26, has kept largely out of the public eye.

He has taught a seminar at New York University and founded a strategic consulting group, Miller Strategies. He is also the chairman of Liberty Art Title, a company that insures artwork, according to a recent article in an East Side newspaper, Our Town.

Mr. Miller’s political aspirations were dealt a blow in 2005 when he came in fourth in the Democratic mayoral primary. The hard-charging speaker, who clashed with Mayor Bloomberg from his council pulpit, was dogged during the campaign by questions about his spending of $1.6 million in taxpayer dollars to send out a campaign-style mailing, and about whether his campaign had violated spending regulations.

To pay for the mailings without having to go through a competitive bidding process that might have attracted attention, Mr. Miller’s council split the large mailing order into 150 smaller bundles, nearly all of which were less than $5,000.

Mr. Miller’s chief of staff, Charles Meara, fielded questions about the purchasing system at the time. Mr. Meara stayed on after Mr. Miller left office and is chief of staff to Ms. Quinn.

Ms. Quinn brought in a new aide to run her budget department, firing Mr. Miller’s budget director and hiring a lawyer, Michael Keogh. Mr. Keogh no longer works for the council, but Ms. Quinn has declined to say whether he was fired.

A council member of Brooklyn, Lewis Fidler, said that since leaving office, Mr. Miller has made it a habit to pop into City Hall every few months, dropping by the council members’ lounge for visits.

“He is always a pretty positive, happy guy. But he just says to us, ‘Look, let me tell you something, I am enjoying life, all the things that I put aside — my wife, my kids, TV, sports,'” he said. “And it rings true. It doesn’t sound like he’s faking it. He’s truly at peace and enjoying himself.”