Norman Seabrook, the longtime union boss of New York City's correction officers, will spend at least four years in prison, following his sentencing today for accepting a six-figure kickback in exchange for steering union retirement benefits into a sketchy hedge fund.

The 58-month sentence was handed down by Judge Alvin Hellerstein on Friday, capping off a sprawling federal probe into the corrupt dealings of a man who once ranked among New York City's most powerful labor leaders. For two decades, Seabrook ruled over the 20,000-member Correction Officers’ Benevolent Association, helping to dictate jail operations and frequently acting as a roadblock to reforms.

While he did "major good" for union members, Seabrook was "blinded by his own sense of importance and his desire to benefit himself after benefiting others for so long," the judge said on Friday, the NY Post reports.

Among his many duties as COBA boss, Seabrook controlled the union's finances, including the administration of a city-funded benefits program that invests more than $70 million for correction officers’ retirements.

In 2013, he declared that "it's time for Norman Seabrook to get paid," according to prosecutors. Soon after, Jona Rechnitz, a de Blasio donor who's admitted to bribing several law enforcement officials, delivered $60,000 in a Ferragamo bag to Seabrook. As part of the deal brokered by Rechnitz, Seabrook had agreed to invest millions of dollars into a now-defunct hedge fund called Platinum Partner, run by Murray Huberfeld. Most of that money was lost.

"Tens of thousands of hardworking correction officers once looked to Norman Seabrook as their leader and champion," Manhattan U.S. Attorney Geoffrey S. Berman said in a statement. "Seabrook now stands convicted of betraying them for a bag full of cash and the promise of more. His conduct resulted not simply in the membership’s loss of faith in its leader, but the loss of millions of dollars in retirement benefits due to union members."

Following the sentencing, Seabrook was reportedly unapologetic. “There is no evidence that I ever intended for any union member to lose a dime," he said. "I always believed these investments would make money."

Under the terms of the sentence, Seabrook, Rechnitz, and Huberfeld will be required to pay back $19 million in lost investment. Huberfeld is due to be sentenced next week, and faces a maximum sentence of five years in prison. Rechnitz, who has pleaded guilty to a slew of other charges, including buying access to the de Blasio administration, is set to be sentenced on April 4th.