The federal corruption trial of John O’Brien and two of his top aides has focused so far on patronage at the Probation Department, but the defense is about to broaden the discussion by examining the hiring of politically connected court officers.

Judge William Young ruled on Friday that defense attorneys can introduce a trove of documents showing Senate President Therese Murray’s office was deeply involved in getting court officer jobs for politically connected candidates, bolstering the defense’s argument that O’Brien’s hiring practices were no different than those of others in state government.

Among those who got Murray’s support for court officer jobs was Patricia Bellotti, the sister of Norfolk Sheriff Michael Bellotti and daughter of former Attorney General Frank Bellotti. Murray in 2008 went to bat for Bellotti to get a position at Dedham Court Complex, even though it is not in Murray’s Senate district.

Another successful candidate who received Murray’s support was Richard A. Musiol, the father of Murray’s chief of staff. The elder Musiol got a job in 2008 at Wareham District Court as he approached his 60th birthday despite having no relevant experience. According to his application, Musiol had been in the restaurant business as a bartender and line cook for more than 25 years except for a brief stint as an electrician’s assistant.

It is unclear what the qualifications for the job were back in 2008, but the current qualifications include a minimum of a high school diploma with an associates degree preferred; at least four years of experience in security, law enforcement, corrections, loss prevention, emergency medical services, or direct care social services; and a preference for some formal training in self-defense. Musiol listed none of those except a high school diploma.

Francine Gannon, who oversaw constituent services in Murray’s office, including herding job requests and recommendations, noted on Musiol’s file that she spoke with Elizabeth Cerda, who was the legislative liaison for then-Chief Justice of Administration and Management Robert Mulligan, and paved the way for Musiol to be hired as an associate court officer.

“Rec’d call from Elizabeth,” Gannon wrote on her case work sheet on Nov. 27, 2007. “Musiol will be ok as ACO.”

Gannon later wrote that she received a call from the elder Musiol that he had been given a physical, including an EKG. “All Set!,” Gannon wrote in large letters when Musiol was officially hired.

Young’s ruling is a blow to prosecutors who filed a motion trying to preclude attorneys for O’Brien, Elizabeth Tavares, and William Burke III from bringing into evidence case files they obtained through subpoena from Murray’s office. The records detail a keen interest by the Senate president and her staffers to go to bat for politically connected applicants for the court officer posts. Defense attorneys are apparently planning to use the documents during their cross examination of Gannon to show the practice was widespread and not limited to Probation, a key element of their defense.

Assistant US Attorney Karin Bell, who filed the motion, tried to convince Young that the court officer lists are unrelated to similar records prosecutors are introducing from Murray’s office regarding probation jobs.

“At most, [Gannon] will be able to testify to the content of her notes, which indicate that she made calls to [the Trial Court] to recommend candidates and, in some instances, the candidates got jobs,” Bell wrote. “Indeed, on their face, the Gannon case files suggest no more than the fact that Senator Murray made recommendations on behalf of candidates for court officer positions and some of her candidates got jobs. There is no indication that the hires were not based on merit or otherwise proper.” Related: Probation intervention helped Lawton along

But William Fick, one of O’Brien’s court-appointed federal defenders, pointed out that the documents are critical to counter the government’s contention that O’Brien ran a rogue agency engaged in a rigged hiring system. Fick says the documents show that Mulligan, as the statutory boss of O’Brien, engaged in the same type of patronage hiring O’Brien did, although the records introduced so far do not indicate any efforts to tamper with the interview process as O’Brien and his aides allegedly did. Fick says the claim that Mulligan was misled by O’Brien is undercut by records showing that the chief justice was doing pretty much the same thing himself. For example, he hired Cerda, the wife of a state representative, to supervise hiring.

“The evidence demonstrates that CJAM Mulligan was himself an active and knowing participant in politically-influenced hiring at [the Trial Court],” Fick wrote. “Testimony concerning Ms. Gannon’s activities in this regard is exculpatory and critical to the defense.”

The defense filed more than 120 pages of documents that had been kept by Gannon, including handwritten notes from her, Murray, and the younger Musiol as well as emails regarding candidates. Gannon, who did similar work for the late congressmen Joe Moakley and Thomas P. “Tip” O’Neill, also held the same job under Murray’s predecessor as Senate president, Robert Travaglini.

In a number of documents, Gannon refers to “Trav” as having interest in certain candidates by making calls or sending emails on their behalf. Gannon would periodically send memos to Murray summarizing the office’s efforts and updates on candidates. Murray’s office apparently went to bat for Mark Chiarenza, a North End resident who was trying to get a promotion from associate court officer, which is an entry level position, to full court officer in Suffolk Superior Court.

“He is also being promoted from ACO to CO,” Gannon wrote in one memo she addressed to Madam President. “(H)is dad close friend of Trav’s who called from hospital bed in tears to express his gratitude to you and Trav. VERY GRATEFUL AND THANKFUL!”

But the records show that not all candidates were successful, mostly because their connections could not override the fact they weren’t a constituent. On one candidate’s application, Murray’s staffer Rick Musiol apparently attached a post-it note in which he wrote, “He isn’t a constituent. TM—do you know him?” he wrote, apparently referring to Murray.

On another, Gannon wrote a note that Cerda had told her that the applicant “did not meet necessary qualifications.” The note was dated about the same time Musiol’s father was hired. Neither of the unsuccessful candidates listed political connections.