William Cellini, Illinois' ultimate political insider who for more than four decades worked quietly behind the scenes to amass wealth and power, was convicted Tuesday for joining an age-old conspiracy scheme that demanded campaign cash for access.

A federal jury convicted the 76-year-old longtime Republican lobbyist and fundraiser of agreeing to use his considerable power at an Illinois teachers pension board to help put the squeeze on a Hollywood producer who wanted to continue to do business with the state.

While such a pay-to-play scheme is sadly all too familiar for Illinois, the conviction of a figure who had built such formidable clout in the background of Illinois politics and government was notable to federal prosecutors who spent the last eight years trying to unravel the criminal actions of the scandal-plagued Blagojevich administration.

"I think it's safe to say that people who stay in the shadows and people who stand behind the people who are in public office are sometimes more difficult to catch," said Assistant U.S. Attorney Christopher Niewoehner, who prosecuted Cellini and has been involved in the investigation since its early days. "But they're exactly the people we're looking hard at. They're the people we want to catch."

Cellini showed little reaction to the verdict Tuesday morning, but his daughter, Claudia, who has been in the courtroom along with some two dozen supporters throughout the 31/2-week trial, leaned forward from her front-row seat and let out an audible gasp.

The jury of 10 women and two men convicted Cellini of conspiracy to commit extortion and aiding and abetting in the solicitation of a bribe. He was acquitted of conspiracy to commit mail fraud and attempted extortion.

Cellini left the courthouse without addressing reporters, but his attorney, Dan Webb, vowed an appeal. Webb also spun the split verdict as a victory of sorts, saying that Cellini was acquitted on what he considered the more serious charges. But the one conspiracy conviction carries up to a 20-year prison term, though the likely sentence would be far less.

With Cellini's guilty verdict, the federal Operation Board Games probe has netted the convictions of 15 individuals, including former Gov. Rod Blagojevich, several of his top advisers and former powerful Chicago Ald. Ed Vrdolyak. Blagojevich is awaiting sentencing for his conviction last summer on sweeping corruption charges that included trying to sell the U.S. Senate seat vacated by President Barack Obama.

U.S. Attorney Patrick Fitzgerald lamented that the rampant corruption that engulfed the Blagojevich administration came on the heels of the scandal that brought down former Gov. George Ryan.

"Obviously, some people didn't get the message," Fitzgerald told reporters.

While never elected to office over the last four decades, Cellini held powerful sway in the back corridors of the state capital.

Hired as Illinois' first transportation secretary by Republican Gov. Richard Ogilvie, Cellini became a part of the state's GOP infrastructure. While he held the unassuming title of treasurer of the Sangamon County Republican Party in his native Springfield, Cellini raised massive amounts of money for favored candidates and built a thriving real estate development, construction and investment business.

With Gov. Jim Thompson's election launching a quarter-century of Republican control of the governor's mansion in 1976, Cellini's power and wealth increased.

From his transportation background, Cellini went on to become the longtime executive director of the politically influential Illinois Asphalt Pavement Association. He also led a group in obtaining the state's first casino gambling license.

"I think he was a victim of his own myths," said Thompson's successor, Gov. Jim Edgar, a close friend of the Cellini family. Edgar, who hired Cellini's sister, Janis, as his patronage director, said he was "disappointed and surprised" by the verdict.

"He had influence, but a lot of people have influence. He never had the power that people made it out to be. Sure, that helped him in some ways. But it ended up hurting him," Edgar said.

The charges against Cellini centered on his longtime influence at the Illinois Teachers' Retirement System, the state pension fund for public school teachers outside Chicago. To keep from losing his clout there after Blagojevich became the first Democratic governor of Illinois in more than a quarter-century, prosecutors alleged, the multimillionaire Republican fundraiser agreed to pick firms to manage TRS' hundreds of millions of dollars in investments on one key condition — that they had contributed to Blagojevich's campaign.

Prosecutors alleged that two key Blagojevich advisers, Antoin "Tony" Rezko and Christopher Kelly, targeted Hollywood producer Thomas Rosenberg after learning he had not made any contributions to the then-governor's campaign even though his investment firm had a lucrative deal with TRS.

Cellini, working with corrupt TRS board member Stuart Levine, was to relay the message to Rosenberg that a $220 million allocation from TRS would be held up until he made a campaign contribution.