Rep. Mark Walker, R-Sandy, resigned and ended a House Ethics Committee investigation Monday into allegations he attempted to bribe his GOP primary opponent in his unsuccessful race for state treasurer.

Walker said in a letter delivered Sunday to House Speaker Greg Curtis, R-Sandy, that he had decided not to serve out the five months remaining in his term "(b)ecause I cannot in good conscience continue to put my family through the attacks and turmoil ... ."

After being advised by Legislative General Counsel John Fellows that the ethics committee no longer had jurisdiction over Walker after his resignation, members dismissed the complaint filed against him by five lawmakers and adjourned.

"Business as usual," complained one of the five, Rep. Phil Riesen, D-Salt Lake.

But the five lawmakers — a list that includes two Republicans — are considering filing a new ethics complaint against an unnamed legislator said to be involved in the alleged bribe. That legislator is widely rumored to be a member of House GOP leadership.

And the criminal investigation by two county attorneys appointed by Attorney General Mark Shurteff, a Walker supporter, continues into the allegations made by Walker's primary opponent, Richard Ellis. Ellis won the GOP run-off with nearly 60 percent of the vote.

Ellis, the chief deputy state treasurer, said Walker offered him the opportunity to keep his job at a much higher salary if he dropped out of the race. Walker has denied any wrongdoing, but has said he told Ellis he wouldn't fire him or anyone in the treasurer's office if he won.

"To me, it seems like it validates my position, validates the allegations," said Ellis, who attended the ethics committee meeting to testify under subpoena. He said he was surprised to hear Walker resigned.

Before dismissing the complaint, one member of the ethics committee, Assistant Minority Whip Carol Spackman Moss, D-Salt Lake, pressed to continue the investigation to determine if any other lawmakers committed an ethics violation in connection with the allegations.

"Others may be guilty," Moss said. "I believe this hearing was in part to see if other people were involved. The fact that Rep. Walker resigned takes him off the table, so to speak" but doesn't affect any other lawmaker.

Fellows, though, said legislative rules would not permit the investigation to go forward now that Walker had resigned. Fellows said later in an interview any further investigation would require a new complaint be filed against a specific lawmaker.

That's what the five lawmakers who came forward with the ethics complaint against Walker are now considering, according to their legal counsel, David Irvine. "We're still exploring options and there are several," Irvine said.

The ethics complaint states that Walker "offered to use his position as a legislator and his legislative connection with an unnamed member of the legislative body to secure a legislative appropriation in order to bribe another government official," Ellis.

Ellis had stated in his original elections complaint, filed with Lt. Gov. Gary Herbert, that Walker assured him he could make the pay raise "happen and that he had talked with 'the person' who could make it happen."

Irvine said he was "not 100 percent sure" the person referred to was Curtis. But, Irvine said, the House speaker certainly was among the handful of GOP leaders able to make such a commitment.

He also suggested Walker was forced out, presumably to stop the investigation. "It's pretty clear that the House leadership has made a decision to sacrifice, in chess terms, a pawn to save the king," Irvine said.

The House speaker was upset at the suggestion he may be the target of a new ethics complaint. "I refuse to comment on these unfounded, mean-spirited, politically motivated accusations," Curtis said.

As for Walker's decision to step down, Curtis said he was "disappointed Mark felt it was was necessary to resign, but he determined that it was in his own best interests for himself and his family to put this matter behind him and move forward."

Walker, 32, first elected to the Legislature in 2004, is expected to be replaced by the GOP candidate for his seat, Brian Monsen. Monsen's Democratic opponent, Laura Black, lost to Walker two years ago by just 18 votes.

Walker did not return telephone calls Monday and his voice mail referred callers to his attorney. His campaign manager, Steve Hunter, said Walker and his family planned to spent the next few weeks with his family, including his pregnant wife, at a secluded cabin.

Hunter said he talked with Walker on Sunday about his decision. "He just said, 'I just can't do this to my family anymore. I know I should stay and fight and get the story about Richard and everything out there,'" Hunter said.

Walker considered how his resignation would be seen, Hunter said. "He feels like if he resigns, everyone is going to say he's covering the unnamed legislator," Hunter said. "There's no one to cover for. There's no one there."

Walker said in his letter of resignation that he will fully participate with the Davis and Weber county attorneys named by the attorney general to handle the criminal investigation into what would be a class B misdemeanor.

"I believe that when all of the facts are presented they will show that although I may have made some mistakes in judgment I have done nothing which would warrant ethical sanction or a criminal charge," Walker wrote.

Davis County Attorney Troy Rawlings said Monday the ethics committee's dismissal of the complaint "has no impact on what we have been asked to look at by the attorney general's office."

There apparently already has been political fallout from the ethics complaint.

Last week, reports surfaced about an incident with a female legislative intern and Rep. Steve Mascaro, R-West Jordan, one of the five lawmakers who filed the ethics complaint. Mascaro said he did nothing wrong and blamed retribution by his party leaders.

"I sense heavy-handed backroom political deals here," said Utah Democratic Party Chairman Wayne Holland. He said the situation demonstrates the need for an independent ethics commission.

"We can only hope Walker's resignation will not derail the attempt of a few courageous lawmakers to force our GOP-dominated Legislature to work for us instead of lobbyists and their cronies."

Contributing: Ben Winslow