Every weekday, for the next month or two, former state Probation Department boss John O’Brien will walk into the federal courthouse in South Boston and listen as prosecutors try to send him to prison. There was a time not too long ago when it looked as if O’Brien would have the company of several Beacon Hill lawmakers at his defendant’s table. The Lowell Sun reported two years ago that the federal investigation into rigged hiring at Probation was expected to ensnare four sitting state lawmakers. Lawmaker indictments never materialized. O’Brien’s only co-defendants are a pair of former aides.

In some ways, though, prosecutors are using O’Brien’s federal corruption trial to deliver rougher treatment to Beacon Hill than they would have, had they rung up a handful of lawmakers for participating in O’Brien’s alleged jobs-for-favors trade. Instead of trying individual lawmakers, federal prosecutors are using the O’Brien trial to smear mud all over Beacon Hill’s political culture. The entire State House is on trial right now.

Sen. Mark Montigny figures prominently in the investigation into O’Brien’s tenure that outside lawyer Paul Ware prepared for the state Supreme Judicial Court. Ware’s report served as a roadmap for the case prosecutors are trying to build against O’Brien and company. Ware reported that Montigny was a prolific sponsor of candidates for patronage jobs at Probation, and that he was also one of the richest beneficiaries of political donations from Probation employees, in what Ware described as a “pay for play” culture. Montigny hasn’t been indicted in the Probation case. Instead, prosecutors have flung his dirty laundry around the courtroom, noting that Montigny secured a Probation job for his then-21-year old girlfriend. A prosecution witness testified last week that he had “grievous concerns” about O’Brien’s alleged insistence upon hiring Montigny’s girlfriend, noting that she was “woefully inadequate as far as her qualifications.”

The Globe dubbed Rep. Thomas Petrolati, a former top lieutenant to House speakers Sal DiMasi and Robert DeLeo, the king of Probation patronage four years ago. During the first week of the trial, two separate Probation Department employees testified that they made cash donations to Petrolati’s campaign account. The contributions don’t appear on the state’s campaign finance database, and they appear to run afoul of a number of state campaign rules, which prohibit cash donations over $50, require disclosure of donations above that amount, and forbid politicking while on state property. The O’Brien trial testimony has state employees bundling cash donations for Petrolati while in a state building cafeteria.

Senate President Therese Murray has come in for special scrutiny during the trial’s early days. Testimony has Murray personally pushing a patronage job for the son of a state judge; according to trial testimony, the mother of the job-seeker Murray aided, Patrick Lawton, was a friend of Murray’s. Lawton turned in a “dreadful” interview performance, but Murray and O’Brien muscled him into a job anyway; he later lost the job, after being arrested on drug charges. Murray’s office also championed the cause of another would-be Probation employee, Patricia Mosca, who told Murray’s constituent services director that she was only looking for a Probation job as a way of fattening her state pension. Instead of turning Mosca away, Murray’s office put its weight behind the pension play, and landed a job for Mosca in a Plymouth courthouse. “She’s very excited and grateful to you,” a Murray aide 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.”

On cross-examination the same Murray aide described how the Senate president helped engineer a court officer job for the father of Murray’s chief of staff, and secure a promotion for the sister of Norfolk County Sheriff Michael Bellotti. Documents filed by the defense also indicated that Murray’s predecessor, the lobbyist Robert Travaglini, is using Murray’s office to place patronage hires.

That’s one job for a senator’s young girlfriend, two instances of a state rep allegedly collecting cash bundled from inside the state cafeteria, and an ever-growing list of questionable patronage jobs. And the jury hasn’t even met the House speaker’s godson yet. The trial, and the ugliness for Beacon Hill, is still just getting started.