Washington ? A former top aide to Rep. Bob Ney, R-Ohio, pleaded guilty Monday in the Jack Abramoff influence peddling scandal, admitting he conspired to corrupt Ney, his staff and other members of Congress with trips, free tickets, meals, jobs for relatives and fundraising events.

The criminal investigation of Abramoff’s lobbying operation has now claimed Abramoff and three former congressional staffers: Neil Volz on Monday, as well as Tony Rudy and Michael Scanlon, who both worked for former House Majority Leader Tom DeLay, R-Texas.

Abramoff and the three former congressional aides are now government witnesses whose prison terms may depend in part on how cooperative they are with federal prosecutors in the investigation involving lawmakers, their aides and members of the Bush administration.

“They’re singing for their supper,” Ney lawyer Mark Tuohey said. The lawyer said many of the allegations regarding Ney are incorrect and that “the government has been sold a bill of goods by Mr. Abramoff.”

Tuohey said Volz was under “extraordinary pressure” to assist the Justice Department probe.

Volz said he engaged in a conspiracy, the intent of which was “to influence members of Congress in violation of the law.”

In a nine-page document that focused on Ney’s conduct, Volz enumerated 16 actions he said his old boss took on behalf of Abramoff clients. During the period, from January 2000 through April 2004, Volz said Abramoff and his lobbyists gave Ney and members of his staff trips to Lake George in New York state, New Orleans, the Fiesta Bowl in Tempe, Ariz., in 2003, and a weeklong golfing retreat to the Old Course at St. Andrews in Scotland, with a second leg to London.

In addition, Volz wrote, Abramoff gave the congressman and his staff numerous tickets to concerts and sporting events in the Washington, D.C., area; regular meals and drinks at restaurants including Abramoff’s restaurant Signatures, and unreported use of Abramoff’s box suites at the MCI Center Arena in Washington and Camden Yards Stadium in Baltimore for political fundraisers for Ney and for candidates and political organizations he supported.