A former congressional staffer who golfed in Scotland at lobbyist Jack Abramoff's expense was ordered Monday to spend 12 weekends in jail, avoiding a lengthy prison sentence after helping investigators pursue two congressman in the influence-peddling scandal.

Mark Zachares, a former aide to Alaska Republican Rep. Don Young, also was sentenced by U.S. District Judge Ellen Segal Huvelle to four years probation and 200 hours community service and ordered to pay $4,000 fine. His attorney, Edward MacMahon, said afterward his client was "gratified that the judge showed him mercy."

Zachares could have faced years in prison after pleading guilty to conspiracy three years ago. But in a recent court filing prosecutors requested a lighter sentence and revealed his help to the FBI, including secretly taping a phone call to another witness to one congressman's travel.

Prosecutors did not identify the two congressmen Zachares helped investigate but said they ultimately were not charged for accepting travel and entertainment from Abramoff and other lobbyists.

Zachares is one of 20 people convicted in the gifts-for-favors scandal set off by Abramoff, a prominent Republican lobbyist before he pleaded guilty in the case. Although several elected officials were investigated, only one — former Ohio Republican Rep. Bob Ney — has been prosecuted. Ney served 17 months in prison. Meanwhile several lower-level staffers on Capitol Hill and officials of the George W. Bush administration have paid for Abramoff's influence-peddling with convictions, prison time and fines.

Several lawmakers have said they were unaware of their aides' wrongdoing and did nothing illegal, but the prosecutors' court filing in Zachares' case suggests that at least some lawmakers took gifts but escaped prosecution because of legal issues.

Zachares took an all-expense paid trip with Abramoff, then-Rep. Tom Feeney, R-Fla., and five others in August 2003 valued at more than $160,000 to play golf at Scotland's St. Andrews and other world-famous courses. Zachares then lied about it on disclosure forms.

Feeney may have been among the congressmen Zachares helped investigate. The prosecutors said Zachares provided "extensive, detailed, and valuable eyewitness information" about one congressman's travel but that the investigation of that lawmaker was ended after he asserted his privilege under the Constitution's separation of powers provisions. The investigation into Feeney was dropped last year after the U.S. Circuit Court of Appeals in Washington ruled that information he divulged to the House Ethics Committee about the trip could not be used against him because of the separation of powers.

The investigation of another congressman, who prosecutors said was not known to have accepted gifts before Zachares informed the FBI, was dropped because of "legal and evidentiary issues," their court filing said.

Others investigated in the Abramoff scandal included former House Majority Leader Tom DeLay, R-Texas; former Reps. John Doolittle, R-Calif., and J.D. Hayworth, R-Ariz.; and former Sen. Conrad Burns, R-Mont. All have said the Justice Department has told them they won't be charged.

Zachares is one of two staffers who worked on the transportation committee chaired by Young to be charged. The other, Fraser Verrusio, is to go to trial in January, the only pending Abramoff case.

Zachares also acknowledged accepting tickets to more than 40 concerts and sporting events worth more than $30,000, numerous free meals at a restaurant Abramoff owned, multiple free rounds of golf at Abramoff's country club and $10,000 cash from Abramoff shortly before moving to Washington to work for Young. He did not report the cash payment or event tickets as required on his House financial disclosure form.

Zachares, a former prosecutor, voluntarily surrendered his law license but said in a court filing he hopes to be reinstated someday.

The 52-year-old, married father of two daughters cried as he apologized for his crimes in court. He said Abramoff helped him get the job with Young's committee. Zachares admitted he gave Abramoff government-insider information useful to Abramoff's clients or for seeking new clients.

Zachares told Huvelle he supports his family with sales of intellectual property. She said the weekend jail sentence will allow him to continue his job.