NEARLY SIX YEARS after the Probation Department patronage scandal exploded into public view, almost four years after three top officials were indicted, 18 months after their convictions, and nearly one year to the day after the trio filed their appeals, the case remains unsettled.

No one has served time, no one has paid a fine, and no one has yet lost their pension despite the felony convictions. And the federal Appeals Court has just granted the third deadline extension for filing briefs despite warnings each time that no more extensions would be granted.

A spokeswoman for US Attorney Carmen Ortiz said the time intervals are par for the course in such a complex set of cases. “This was a very lengthy trial, and in these types of cases extensions are not unusual,” Christina DiIorio-Sterling wrote in an email.

But even given the breadth of the case, which took two months to try, the appeals are stretching out nearly double the average length of time for a criminal appeal in federal court. Perhaps the cause is the complexity of the case or perhaps the delays may be related to reports that the US Attorney’s office is putting pressure on former Probation commissioner John O’Brien to spill all he knows as prosecutors continue to pursue the chance to haul lawmakers into court.

In May 2010, the Boston Globe ran its scathing series on patronage at the Probation Department. O’Brien was immediately suspended amid an ongoing investigation by the Trial Court following the Globe story and he and two deputies, Elizabeth Tavares and William Burke, were charged in federal court two years later. O’Brien, Tavares, and Burke were found guilty on July 24, 2014, and Judge William Young sentenced the trio four months later, with O’Brien receiving 18 months in prison, Tavares handed a 90-day prison term, and all three sentenced to probation.

Young refused to stay their sentences and ordered them to jail. But on Dec. 12, 2014, lawyers for the three officials filed appeals and were granted stays in their sentences because, as the three-judge panel wrote, “the court is persuaded of a sufficient probability that the appeals present a ‘substantial question’” that could result in the conviction being overturned.

The initial timetable called for the briefs to be filed on Aug. 10, but in July the court granted an extension to Oct. 9. The judges wrote, though, “We are disinclined to grant a request for further enlargement of this deadline.” In September, the court granted another delay to Dec. 7 at the defense request, again expressing the judges’ disinclination to allow further extensions. But once more, on Nov. 25, the panel allowed a defense motion for delay until Jan. 7, 2016, but this time was more forceful in drawing the line. “No further extension of this deadline should be expected,” the judges wrote.

According to the latest federal court data, the average length of time from filing the notice of appeal to issuing the final order in a criminal appeal in fiscal 2014 was 10.8 months; the Probation case will have taken 13 months to file briefs if the filing date is not postponed again. It typically takes another 6.4 months to complete a case after the briefs are filed. The court data indicate the First Circuit Court of Appeals based in Boston has the second lowest number of appeals among the 12 circuit courts and is among the slowest in dealing with them.

Each motion for delay by the defense in the Probation case has included a note that prosecutors do not oppose the request, despite the sentences hanging over the three.

“If someone is already incarcerated, then prosecutors aren’t normally in any rush” to expedite the appeal, said Suffolk Law School Professor Rosanne Cavallaro, a former private attorney and assistant attorney general who teaches, among other classes, criminal law. “If someone is out, they haven’t served their sentence, maybe there is a tiny bit more urgency from the prosecutors’ perspective. In my experience, if the parties agree, it’s really kind of a courtesy extended to the lawyer.”

There is the possibility that prosecutors are continuing to apply pressure to O’Brien to cooperate in an investigation of state lawmakers, and forcing him to serve his time could undermine that effort. The Globe reported in October that O’Brien has been forced to testify before a grand jury under a grant of immunity about what lawmakers did and knew regarding the patronage scheme.

But with the statute of limitations on the crimes themselves having expired in May, it is unclear what charges prosecutors are pursuing. The Globe story speculated some of those who testified could be investigated for perjury but they were, by and large, low-level state representatives. House Speaker Robert DeLeo did not testify at the trial, though prosecutors labeled him an unindicted co-conspirator. He did testify under oath to Paul Ware, hired by the Supreme Judicial Court to investigate the probation scandal. But it’s unclear whether that deposition could be used as the basis for federal charges.

“Ordinarily speaking, the federal prosecutors would be charging someone under a federal statute,” says Cavallaro, who emphasized she had not studied the probation case in depth. “I’m not sure what that federal nexus would be with a state investigation.”

The appeals also have an impact on the pensions for the three longtime state employees. When the sentences were handed down, the state Pension Board halted payments but did not revoke the pensions. A spokeswoman for State Treasurer Deb Goldberg said the board continues to pay out the monthly pensions in order for taxes to be deducted but then places the net amount in escrow, pending a final decision by either the Pension Board or the Appeals Court.