Robert Mulligan, the former chief justice for administration and management of the Massachusetts Trial Court, was aware of hiring irregularities at the state Probation Department in 2006, but didn’t feel like he had the power to put the brakes on runaway Probation patronage, a former high-ranking Probation Department official testified Friday.

Edward Dalton, a retired regional supervisor in the Probation Department, detailed his April 2006 visit to Mulligan’s Wellesley home while testifying Friday in the federal corruption trial of former Probation commissioner John O’Brien and two former top aides, Elizabeth Tavares and William Burke III. Prosecutors allege that O’Brien ran Probation like a criminal enterprise, overseeing a sham hiring system that secretly steered patronage jobs to politically connected individuals. The prosecution claims O’Brien traded jobs for political clout on Beacon Hill and deceived Mulligan, who had to approve all employment actions, by claiming that Probation hiring was based on merit.

A former top aide to O’Brien, Francis Wall, has previously testified that O’Brien and former House Speaker Tom Finneran wrested control of the Probation Department away from the judiciary in 2001, on the understanding that O’Brien would be a “proponent of patronage.” Mulligan technically oversaw the Probation Department, which is a branch of the Trial Court, and he had final approval over all Probation hires, but he had almost no leverage over how the department operated.

Numerous witnesses in the O’Brien trial have testified that O’Brien maintained tight control over Probation hiring after 2001. They’ve said O’Brien would routinely have the names of politically connected job-seekers passed to Probation officials sitting on job interview panels, on the understanding that those candidates would be pushed through to the final interview round; once in the final round, O’Brien would order aides to hire specific individuals, and the aides would contort interview scores to reflect predetermined outcomes.

Dalton testified that he drove to Mulligan’s home after the judge began asking around about questionable hiring practices at Probation. Dalton said Mulligan reached out to him through Ronald Corbett, a former Probation official who was working as the chief administrator of the Supreme Judicial Court. “He said the chief justice was concerned about [Probation] hiring practices, and would I be willing to have a conversation with him?” Dalton testified.

Dalton said he told Mulligan that although he had been involved in numerous politically-tinged interviews up through the year 2000, he had only participated in one Probation job interview panel since O’Brien gained control of the department in 2001. In that one interview panel in 2005, Dalton said, Tavares gave him the names of six candidates whom O’Brien wanted advanced to a final interview. Dalton testified that, although he warned Mulligan “my information is dated,” he also said that when he was sitting on frequent interview panels up through 2000, “it wasn’t a choice, you had to put [O’Brien’s preferred candidates] in. It was becoming difficult on all the regional supervisors.” From their conversation, Dalton testified, Mulligan was already aware that O’Brien’s office was passing the names of preferred job candidates to the interview panels.

Dalton added that Mulligan “indicated to me he thought his hands were tied.”

Mulligan, who is now retired, has emerged as a key witness in the Probation trial. The case against O’Brien, Tavares, and Burke is largely built around mail fraud. But the government can’t hang a mail fraud conviction on O’Brien if Mulligan was aware of the hiring shenanigans that were happening at Probation. The case depends on the prosecutors showing that Mulligan was duped by O’Brien into making bad patronage hires. Mulligan is expected to take the stand shortly after the July 4 holiday.

OTHER PROBATION NEWS

Dalton testified Friday that O’Brien repeatedly pressured him in 2000 to help hire the son of a politically wired former state senator. Dalton said that O’Brien intervened on behalf of Doug MacLean when Dalton was interviewing candidates for Probation jobs in Falmouth, Dedham, and Quincy. He said that during a days-long interview panel in Quincy, O’Brien called him directly and asked, “Eddie, why didn’t Doug MacLean make the final list?”

“I said, ‘Jack, do you know he has a record?’” Dalton testified. “He said, ‘What are you talking about?’”

Prosecutors are charging MacLean’s 2005 hiring as a Probation officer in Bristol County advanced a racketeering conspiracy. MacLean, the son of former state Sen. William “Biff” MacLean, has become a prominent fixture at O’Brien’s trial, because he landed a Probation job despite having a history of drug arrests. Earlier this week, another witness testified that he heard O’Brien say in 2004 that he would never hire MacLean, but O’Brien soon relented because “he had a lot of pressure from the Legislature.”