The federal corruption trial of John O’Brien unfolded on two levels. It was equal parts law enforcement exercise and political soap opera. The trial of O’Brien, the former state Probation Department commissioner, and two former deputies, Elizabeth Tavares and William Burke III, ended Thursday afternoon in a torrent of guilty findings. But even before a dozen jurors convicted O’Brien, Tavares, and Burke of racketeering conspiracy, the Probation trial had flung heaps of dirty laundry all over Beacon Hill.

Under O’Brien, Probation ran an elaborate operation that catered to state lawmakers’ patronage requests. Numerous witnesses have said that O’Brien frequently rigged Probation job interviews to favor job candidates with ties to powerful Beacon Hill lawmakers. The O’Brien jury rejected defense attorney claims that US Attorney Carmen Ortiz tried to criminalize the way Beacon Hill has done business for years. They found that O’Brien, Tavares, and Burke turned patronage into fraud.

The O’Brien verdicts tied several high-profile lawmakers to fraudulent hiring at the Probation Department. These lawmakers include Senate President Therese Murray, House Speaker Robert DeLeo, Rep. Thomas Petrolati, Sen. Mark Montigny, as well as a pair of fallen House speakers, Sal DiMasi and Thomas Finneran.

No trial evidence suggested that these lawmakers were aware that O’Brien was rigging hiring and falsifying documents – the specific acts that led the jury to convict O’Brien of mail fraud. The O’Brien trial was damning to Beacon Hill for a different reason. Lawyers on both sides of the case described the state Legislature as consumed by small-time favor trading. They argued that, for Beacon Hill lawmakers and powerbrokers, putting a thumb on the scale is a way of life.

When Janet Mucci, Probation’s longtime human resources director, called a Probation official and asked him to advance a half-dozen legislatively-sponsored job candidates through a job interview, this is how she explained the request: “Jack had had a meeting over at the State House yesterday… and again that triggered a lot of this. You know, when he got everything he wanted this year in the budget moneywise, so they feel like they did that for him … and obviously he needs to do this for them.”

Edward Dalton, the recipient of Mucci’s 2000 call, taped Mucci’s voicemail and hung on to it for a decade. Dalton handed the tape over to Paul Ware, the lawyer who investigated Probation hiring for the state Supreme Judicial Court. The message received prominent play in Ware’s 2010 report to the SJC, and prosecutors claimed at trial that it was evidence of a quid pro quo between O’Brien and lawmakers.

More than anything else, though, Mucci’s call to Dalton indicates that, to the people who practiced it, the rationale for patronage and favor-trading on Beacon Hill was obvious: When legislators took care of you, you had to jump when they called. And, as testimony in the O’Brien trial showed, the calls came constantly.

Take, for instance, Senate President Murray. Testimony in the O’Brien trial showed Murray’s office pushed O’Brien for a job for Patrick Lawton, who had a drug problem but hailed from a politically connected family. Murray’s office pushed O’Brien to hire Lawton, even after Lawton submitted a job interview performance one state judge described to jurors as “dreadful.” Testimony showed Murray was personally involved in pushing Lawton on O’Brien.

Murray also pushed Probation to hire Patricia Mosca. Mosca was a Democratic state committeewoman who worked for the state, and who was nearing retirement age. She turned to Murray for help boosting her pension. Murray’s aide, Francine Gannon, told jurors Mosca “was rambling about how she wanted to increase her pension. She figured this all out.” By landing in Probation, Mosca was able to retire five years early. “She’s very excited and grateful to you,” Gannon wrote in a memo to the Senate president. “Her interview was just OK, she knows it was because of your intervention that she was selected.”

O’Brien’s defense attorneys tried to show that there was nothing unusual about the patronage requests the Probation commissioner received from Murray. This argument didn’t make Murray look any better. Murray pushed the state Trial Court to hire Richard Musiol, the father of her chief of staff, as a court officer. At the time, Musiol was working as a short-order cook. Defense filings also show Murray took sides in a battle for chief court officer at the Dedham courthouse. Murray backed Patricia Bellotti, after Bellotti’s brother, the Norfolk County sheriff, lodged a call to the Senate president.

Defense filings also show Murray’s predecessor, Robert Travaglini, used Murray’s staffers to lodge his own patronage requests, years after leaving the Legislature. Travaglini now works as a lobbyist on Beacon Hill.

One of Murray’s fellow senators, Mark Montigny, pushed O’Brien to hire his then-24-year old girlfriend. One judge who interviewed Montigny’s girlfriend described her as “woefully inadequate as far as her qualifications.” The same judge said the girlfriend turned out to be an excellent probation officer.

Trial testimony also showed that legislators leaned hard on O’Brien to hire the son of his predecessor, former Sen. William “Biff” MacLean. Doug MacLean had a history of drug arrests. At one point, O’Brien vowed that MacLean’s history was so checkered that he would never get a Probation job “on his watch.” But O’Brien relented months later – because, as he told one witness, “I’m getting tremendous pressure” from legislators.*

Pressure on O’Brien also came from another senator, Marc Pacheco. O’Brien’s former legislative liaison testified that Pacheco was “very territorial” about probation hiring, saying Pacheco “didn’t want anyone in his court that didn’t share the same zip code as him.” The first justice of the Taunton District Court, Kevan Cunningham, testified that O’Brien swung a chief probation officer’s job to Pacheco’s favored candidate. Cunningham voiced doubts about the candidate, Joe Dooley, to O’Brien. But O’Brien told Cunningham he couldn’t pull his support from Dooley: “He said that Pacheco was putting enormous pressure on him.”

Francis Wall, a former top O’Brien aide, provided damning testimony about the extent to which O’Brien rigged hiring for lawmakers. But Wall also testified that lawmakers had their hands in Probation hiring long before O’Brien’s rise to power. He told defense attorneys that, before O’Brien and Speaker Finneran seized control of Probation hiring, local judges and lawmakers would divvy up patronage jobs evenly; one of O’Brien’s attorneys described the practice as “one for you and one for me.”

Together, Wall said, O’Brien and Finneran in 2001 turned Probation patronage from a retail operation to a wholesale one. Finneran rewrote state laws to concentrate patronage hiring in O’Brien’s hands. He did so, Wall testified, after O’Brien committed to being a “proponent of patronage.”

The jury verdict found O’Brien had given illegal gratuities to several House lawmakers, including Speaker DeLeo, Rep. Thomas Petrolati, Rep. Michael Moran, Rep. Kevin Honan, Rep. Anne Gobi, and former rep Robert Rice. The Petrolati gratuity stemmed from O’Brien’s decision to hire the lawmaker’s wife, even though, at the time of her hiring to a manager’s position, Kathleen Petrolati had no college degree and no criminal justice background.

Eight illegal gratuities came in the form of no-interview jobs that ran through DeLeo, to other lawmakers. The lawmakers testified that they saw nothing unusual about the opportunity to place people in Probation jobs, sight-unseen; in her closing argument, Assistant US Attorney Karin Bell described the lawmakers as moonlighting as HR personnel for the Probation Department.

O’Brien sometimes expressed doubts to government witnesses about his role in the Legislature’s patronage pipeline. “He said he had to eat these people, he had to eat the probation candidates,” O’Brien’s legislative liaison, Ed Ryan, told jurors. Mucci, O’Brien’s HR director, recalled O’Brien pointing up at the State House and saying, “They’re a bunch of pigs. It’s never enough.”

Defense attorneys repeatedly argued that O’Brien was being prosecuted for playing a patronage game everyone on Beacon Hill played. They repeatedly insisted that O’Brien hadn’t invented Beacon Hill patronage – and threw dirt on lawmakers, past and present, in the process.

Stellio Sinnis, one of O’Brien’s attorneys, noted that, when Travaglini was Senate president, he routinely sent patronage candidates to the Trial Court. “Why are you getting applications from the Senate president’s office?” Sinnis asked the former chief of the Trial Court, Robert Mulligan. “What possible role could the Senate president have in hiring court officers?”

At another point, John Amabile, an attorney representing Burke, asked a state judge if it would be correct to say politics influences courthouse hiring “up and down, from janitor to judges?” The judge, Bertha Josephson, replied, “I suppose that’s true.”

Josephson also relayed a damning story about legislative-driven Probation patronage before O’Brien’s rise. She recalled getting ready to chair a mass interview panel involving 18 judges and 70 prospective probation officers, when the then-chief justice of the state’s Superior Court, Suzanne Del Vecchio, passed her a piece of paper with the names of four job applicants written on it. “She was hopeful they’d make it through the interview process,” Josephson testified.

Later, Josephson said, she told told Del Vecchio none of her four candidates had survived the interview. Josephson said Del Vecchio placed a call to the lawmaker she’d gotten the candidates’ names from, Sal DiMasi. At the time, DiMasi was chairing the House’s budget committee. Josephson listened as Del Vecchio cursed out DiMasi, saying, “Next time, send me some goddamn candidates who can make it through an interview.”

* The original version of this story indicated Sen. Mark Montigny pushed O’Brien to hire Doug Maclean, an assertion made during the closing statement of Assistant US Attorney Karin Bell. Witness testimony during the trial, however, indicated the name of the lawmaker or lawmakers who pushed for MacLean was unknown.