By Yereth Rosen

ANCHORAGE, Alaska (Reuters) - The final two defendants in a wide-ranging Alaska corruption scandal will plead guilty to felony charges, avoiding new trials and likely ending a federal investigation that rocked state politics, court documents show.

Former state Representative Vic Kohring filed notice on Monday in U.S. District Court that he will plead guilty to a single count of conspiracy to commit extortion.

Last week, former Alaskan House Speaker Pete Kott filed a similar notice of his intent to plead guilty to a single bribery count.

The change-of-plea filings appear to close a five-year-old federal probe that targeted VECO Corp., then Alaska's largest oil-services company, the late U.S. Senator Ted Stevens and several other Alaska politicians and prominent businessmen.

Stevens, the Senate's longest-serving Republican, was convicted in 2008 of concealing some $250,000 worth of gifts from VECO and lost the seat he held for 40 years.

VECO, for years one of Alaska's most powerful and politically connected corporations, disappeared as a separate entity, its assets purchased by a rival company.

And former Wasilla Mayor Sarah Palin used the scandal to wage a successful 2006 gubernatorial campaign as an anti-corruption outsider.

The scandal broke in 2006, when federal agents raided several state lawmakers' offices. In all, 12 people were charged, and eight wound up in prison.

While Stevens was the best-known target, Kott and Kohring played some of the most memorable roles.

Each was convicted of three felony corruption counts in separate 2007 trials. Much of the evidence came from videotapes made secretly by federal agents of meetings in 2006 between the lawmakers and VECO officials in a Juneau hotel suite.

In one now-notorious tape, Kohring, a Republican from Wasilla, clasped a wad of cash handed to him by Bill Allen, then VECO's chief executive, and asked him: "What can I do for you?"

In another tape Kott detailed his efforts to manipulate the oil-tax bill.

"I sold my soul to the devil," Kott, a Republican from the Anchorage suburb of Eagle River, said in that conversation. To that, Allen replied: "Now I own your ass."

Kott was sentenced to six years in prison and Kohring to 3 and 1/2 years, but both were released early in 2009 on appeal.

They each won new trials after an appeals court found prosecutors had withheld potentially exculpatory evidence.

Stevens' conviction was overturned in April of 2009, and the indictment against him dismissed based on what a federal judge ruled egregious prosecutorial misconduct.

He died in a plane crash in August of 2010.

Allen and former VECO Vice President Rick Smith served prison time after pleading guilty to corruption charges.

They confessed to bribing Kott, Kohring and several other Alaska politicians, including former state Senate President Ben Stevens, Ted Stevens' son, who was paid about $242,000 in what the VECO officials said were phony consulting fees.

Ben Stevens was never charged in the case.

(Editing by Dan Whitcomb and Jerry Norton)