A Brooklyn federal prosecutor whose father was hacked to death pleaded with a judge Monday to go easy on the killers — his own mother and uncle.

Assistant US Attorney Philip Pilmar — whose wealthy businessman father, Howard Pilmar, was murdered by the greedy pair in 1996 — asked Manhattan Criminal Court Judge Gilbert Hong for leniency when sentencing his kin.

“I struggled for years, then came to accept things and move on,’’ explained Philip Pilmar, who was only 10 when his dad was fatally stabbed 40 times in a plot to land $1.2 million in life-insurance payouts.

At the time of his murder, Howard Pilmar, 40, owned a profitable Manhattan office-supply store and two cafes — named Philip’s Coffee Shop after his only child.

His slaying became known as “the Coffee Bar Case.’’

Philip Pilmar, while acknowledging that his father’s death was an “unimaginable horror,’’ insisted that his convicted-killer mom, Roslyn Pilmar, 61, “was kind.

“She taught me to be kind and to value education. Every step of the way, she helped me,’’ the federal prosecutor said during a victim impact statement.

As for his murderous uncle, Evan Wald, 45, Philip Pilmar added that he also “has been a good and kind person to me. He always showed me love.

“Vengeance is not justice,’’ the federal prosecutor said.

But Hong — calling the crime “exceptionally brutal and violent’’ — slammed the defendants with the maximum sentence: 25 years to life behind bars.

“Over 40 stab wounds to the neck, chest, back and forearm and torso … [Howard Pilmar] was ambushed and slaughtered,” Hong said.

The judge dismissed the defense’s assertion that the prison time amounted to a life sentence for Roslyn Pilmar and Wald — noting that the pair lived nearly 20 years in freedom before being nabbed for the murder.

The siblings had long been suspected in Howard’s slaying in the hallway outside his 33rd Street office: Roslyn owed nearly $200,000 after embezzling the dough from her dentist employer, and was the beneficiary of two of her hubby’s life-insurance policies. Wald’s blood also had been found at the crime scene.

But it wasn’t until detectives picked up the stymied case after nearly two decades that people who had previously been mum started talking, helping to finally build a strong prosecution, authorities said.

One person who hailed the judge’s sentencing decision Monday was Philip Pilmar’s grandfather and Howard’s father, 90-year-old Frank Pilmar.

“Every night before I go to bed, I close my eyes hoping to get some sleep. But I can’t get sleep because I keep thinking about the terror and the fear that went through Howard’s mind in those last seconds that he was slaughtered and butchered by those two,” Frank Pilmar told the judge.

The grandpa then directed his emotional statement to Philip.

“That day in March, I lost three things, two of which I can never, ever get back: my son and my business that I worked for for over 50 years. But I also lost Philip, and I know Philip doesn’t want to look at me.

“Sorry about that. But I just want him to know that we love him. The Pilmar family wants him back. … Please, I want you to think one more time, think about coming back. There are no hard feelings on our part. We love you,’’ Frank Pilmar said.

The grandfather added after court that he had brought along his dead son’s soft-leather briefcase in the hopes of giving it to his grandson, but the prosecutor did not stick around long enough to accept it.

“I don’t know when the last time was that I spoke to him. I’ve attempted to speak to him,’’ the grandfather said. “As a matter of fact, at the trial, I was going into the men’s room, and he was leaving the men’s room, and I thought it was Howard because he and Howard have one face.

“But we never spoke a word.”

Roslyn and Wald stood silent and stone-faced as they received their sentences. She was dressed in a black pants suit, while he wore a gray dress shirt and slacks.

Manhattan DA Cy Vance was in the packed courtroom for the proceeding. He left before he could be approached for comment.

Roslyn’s lawyer, Sam Talkin, said outside court, “We’re going to vigorously pursue an appeal, and we hope and expect to be back here and able to try this case again and prove that Ms. Pilmar is not guilty of this crime.”

Wald’s lawyer, Daniel Gotlin, added, “I’m going to file a notice of appeal tomorrow for him. We believe that there are several issues that we believe are good, viable, appealable issues, including the fact that they were denied a speedy trial for 20-some-odd years.

“And as a result of them not being prosecuted in a timely fashion, a lot of the evidence was lost or misplaced.”

Additional reporting by Haley Lerner