A federal judge said on Thursday that John O’Brien’s prison time will be significantly increased because the convicted former Probation commissioner “abused a position of public trust.”

O’Brien was convicted this summer of mail fraud, racketeering, and conspiracy charges in connection with a rigged hiring system he ran at the Probation Department designed to curry favor with lawmakers and other public officials. Judge William Young said that O’Brien “abused a position of public trust and used his position” to increase his power base, a decision that at a minimum will nearly double the amount of prison time O’Brien gets when he is sentenced next week.

After hearing arguments from prosecutors and defense attorneys, Young said he would factor in so-called enhancements on top of federal sentencing guidelines when he hands down sentencing on Nov. 12 for O’Brien and his two top deputies, Elizabeth Tavares and William Burke III.

According to sentencing guidelines, a sentence must be significantly increased if a defendant convicted of racketeering is found by another jury trial or the judge to have engaged in activities that violate the public trust.

Assistant US Attorney Fred Wyshak said after the hearing that, with the enhancements, O’Brien is facing 57 to 71 months in prison. Under sentencing guidelines without enhancements, O’Brien would have been looking at 30 to 37 months behind bars.

O’Brien and Tavares were found guilty in July on multiple counts of mail fraud, racketeering, and conspiracy while the jury found Burke guilty of a single count of racketeering. O’Brien waived a jury trial on the enhancement issue, relying on Young to make the ruling. Prosecutors have not sought enhancements for Tavares and Burke.

Earlier during the hearing, Young denied defense motions for a new trial based on an affidavit from a former employee of the Trial Court’s Security Division, which oversees court officers. The employee, Estela Cordeiro, claimed she had spreadsheets that she said showed that former Judge Robert Mulligan, who was O’Brien’s boss, was not truthful when he said he was not influenced in hiring court officers based on recommendations from legislative leaders, including former House Speaker Sal DiMasi and then-Senate President Robert Travaglini.

William Fick, who represents O’Brien, argued that, had defense attorneys been aware of Cordeiro and her allegations, it would have made a significant difference in undermining Mulligan’s testimony.

“The missing piece and what we have now is a live human being,” Fick told Young. “We could have built a much fuller picture. It would have been extraordinarily powerful evidence.”

But Assistant US Attorney Karin Bell argued that the spreadsheets were nothing new and Cordeiro’s allegations about Mulligan knowing about the, amounted to nothing more than hearsay.

“Frankly, the government’s position is a big, ‘So what?’” she said.

In addition to denying the motion for a new trial, Young also denied a motion from Burke’s attorney for an order of acquittal on his single conviction of conspiracy. While Young admitted he mulled all his actions during the course of the trial and admitted there are things he could have and would have done differently, he said all his rulings were within his judicial power.

“After any trial, all of us go back and think of things we could have done better and that goes for me as well,” Young said. “But defendants are entitled to a fair trial, not a perfect one.”

Correction: An earlier version of this story incorrectly identified where Estela Cordeiro worked in the Trial Court. She was an employee of the Trial Court’s Security Division, not the Probation Department.

Jack Sullivan is now retired. A veteran of the Boston newspaper scene for nearly three decades. Prior to joining CommonWealth, he was editorial page editor of The Patriot Ledger in Quincy, a part of the...