WASHINGTON — A former top aide to Rep. Tom DeLay on Monday became the first person convicted in a two-year fraud and bribery probe involving Indian tribes, lobbyists and public officials.

Michael Scanlon, the Texas Republican's former press secretary, pleaded guilty in federal court to one count of conspiring to offer bribes to public officials and defraud tribal clients of his public relations firm.

In a plea agreement, Scanlon agreed to assist prosecutors investigating the activities of his business partner, lobbyist Jack Abramoff, and their dealings with members of Congress and the Bush administration. (Related item: Scanlon's plea agreement)

Scanlon also agreed to make $19.7 million in restitution to the four tribes he defrauded, in Louisiana, Mississippi, Texas and Michigan. All of the tribes had sought lobbying help in Washington for their gambling operations.

Sentencing guidelines call for up to five years in prison for the offense, but U.S. District Judge Ellen Segal Huvelle could reduce that if the government attests to the 35-year-old Scanlon's cooperation.

In a written statement, Scanlon told the court he and Abramoff provided travel, golf outings, "frequent meals," entertainment, campaign contributions and jobs for officials and their relatives, in exchange for "a series of official acts and influence," which is forbidden by law.

The favors included a 2002 golf trip to Scotland for an unnamed member of Congress, and other trips, meals and entertainment for the lawmaker and his staff. Mark Tuohey, an attorney for Rep. Bob Ney, R-Ohio, has acknowledged that his client is that congressman.

Ney is chairman of the House Administration Committee, a position that gives him jurisdiction over the office space, parking, and expense accounts of his fellow House members and the informal title of "Mayor of the House."

Favors to Ney included "frequent golf and related expenses" at Washington, D.C.-area courses, "regular meals and drinks" at a restaurant owned by the lobbyist on Pennsylvania Avenue and a $10,000 contribution to the National Republican Congressional Committee, given at Ney's request, Scanlon said.

"The level of specificity in this plea agreement should be at least disquieting for the congressman," said Kenneth Gross, an attorney who specializes in ethics issues. But it's unclear "whether they are gunning for him," Gross said.

Ney's spokesman, Brian Walsh, said nothing Ney did was the result of any "improper influence." Walsh said Ney was "one of many people defrauded" by Scanlon.

It was unclear, as well, whether other members of Congress might be caught up in the probe. Scanlon's former boss, DeLay, also took a golf trip to Scotland arranged by Abramoff and apparently paid for by his lobbying clients. DeLay recently was forced to step down from his post as House majority leader because of an unrelated indictment in his home state. (Related items: DeLay money-laundering indictment | DeLay conspiracy indictment)

The investigation also has resulted in the indictment of David Safavian, who was the Bush administration's top procurement official at the White House Office of Management and Budget.

In a criminal complaint filed last week, the Justice Department said Scanlon collected nearly $53 million from 2001 to 2004 from three Indian tribes, promising them lobbying and public relations services. Most of the money went instead into the pockets of Scanlon and Abramoff, the complaint said.

Abramoff was not named in the complaint, but Scanlon's partnership with him has been revealed in a series of hearings in the Senate Indian Affairs Committee, where e-mails between the two described a financial scheme they called "Gimme five."

In a 2001 memo, for example, Scanlon proposed a $3.2 million project for the Louisiana Coushatta tribe that he said would make the tribe "a politician's best friend — or worst political nightmare." The program was to include political research, polling and building a political database, but there is little evidence the work ever was done.