Lawyers for John J. O’Brien, the disgraced former state Probation Department commissioner, said in court filings Thursday that they may call one of the original investigators in the probation scandal as a witness in O’Brien’s long-awaited trial, setting up a potential conflict of interest with a federal judge.

US District Court Judge F. Dennis Saylor IV, who is overseeing the trial, disclosed at a recent court hearing that he was a former law partner of Paul Ware, a private lawyer who conducted an independent investigation into patronage in the Probation Department and who recommended that criminal charges be filed against O’Brien and others.


While Saylor has said that his relationship with Ware was strictly professional, lawyers for O’Brien and a codefendant in the case have made an aggressive request for Saylor to step aside, saying his relationship with the former investigator in the case constitutes at least the appearance of a conflict of interest.

The 11th-hour request has thrown a new tangle into the complex, high-profile trial. The defense team has also asked Saylor to order prosecutors to turn over more evidence in the case and to postpone the trial. Prosecutors have said that the last-minute motions are a strategy to delay the case. The trial is slated to start Feb. 25.

Saylor agreed to hold a hearing Friday on the recusal request. Responding to a request by the judge to describe why Ware would be called to testify, lawyers for O’Brien and a codefendant argued that Ware is a material witness whose original investigation influenced the ongoing criminal proceedings.

“This case exists because of and in the shadow of the Ware Report,” the lawyers said, adding that Ware cherry-picked certain testimony for his report and that grand jury witnesses were subsequently influenced by his report.

The lawyers also said Saylor should not be able to decide whether Ware should be called as a witness, because of his past relationship with the investigator. The lawyers cited court rulings that dictate who should make the decisions.


O’Brien and his former top deputies, Elizabeth Tavares and William Burke, face as much as 20 years in prison on racketeering and other charges in allegedly setting up a rigged hiring and promotion system that favored candidates who were sponsored by state legislators over more qualified candidates. In exchange, the Probation Department received yearly budget increases, helping O’Brien to build his political power as head of an agency where jobs could be bought, prosecutors say.

The accusations were based in large part on a May 2010 Globe Spotlight series into patronage in the Probation Department. Ware, a lawyer with the law firm Goodwin Procter, later conducted an investigation on behalf of the state trial courts and recommended criminal charges against O’Brien and his deputies.

Lawyers for O’Brien and Burke argued that Ware should be considered the original investigator and so can be called as a witness, just as prosecutors could call an investigating FBI agent to the stand. The lawyers also argued that Ware could support their allegations that the case was based on the political motivations of the former head of the state trial court system, who often clashed with O’Brien over regulations and procedure.

The lawyers cited Ware’s own testimony in past cases that he was asked to look only into Probation Department hirings and not any work related to the Legislature or the rest of the trial court system.


“He does have valuable background information about the investigation that led to this prosecution,” the lawyers argued.

Saylor said in a previous court hearing that his relationship with Ware was not social, only professional. A Globe review of the judge’s legal history showed he had worked directly with Ware in at least one case, representing the Massachusetts Port Authority following the Sept. 11, 2011, terrorist attacks.

“There’s no question they practiced professionally, there’s no question they represented MassPort, and there’s no question they were friends at the time,” said Boston lawyer Thomas Dwyer, who represented another party in the matter. “It doesn’t mean anything. It’s not unheard of for a witness to appear before a courtroom where he was a former law partner of a judge.”

Milton J. Valencia can be reached at milton.valencia@globe.com.