Brooklyn District Attorney Kenneth Thompson, a civil rights leader who led the charge in overturning wrongful convictions in the borough, died Sunday, his family said. He was 50 years old.

On Tuesday, he'd said he would take a leave of absence to undergo cancer treatments.

Thompson was elected the first African-American district attorney of Brooklyn in 2013. He had previously worked as a federal prosecutor.

After assuming office in 2014, Thompson created his signature Conviction Review Unit, which became a national model for exonerating the wrongfully imprisoned. It has freed 21 people so far.

"Wrongful convictions not only destroy the lives of those who are convicted and their families, they undermine the integrity of our criminal justice system," he once told News 12.

He also broke ranks with the NYPD and directed his office to stop prosecuting low-level drug offenses that resulted from controversial stop-and-frisk arrests. In that case, he sought to redirect resources toward fighting gun crimes, rape and domestic violence.

Still, he had his critics. The family of Akai Gurley, who was shot to death in an unlit stairwell by former NYPD Officer Peter Liang, was outraged with Thompson's decision to recommend a sentence of no jail time.

Word of Thompson's death prompted an outpouring of condolences from officials and on social media.

"Ken was a dedicated public servant who embodied the highest principles of the law, and his grand presence will be sorely missed," Gov. Andrew Cuomo said in a statement. "A lifelong New Yorker, Ken was known as an effective, aggressive civil rights leader -- and a national voice for criminal justice reform."

Cuomo directed all flags to be flown at half-staff.

"Ken Thompson was a trailblazer who proved himself to be a fierce, unabashed champion for true criminal justice reform," said New York City Council Speaker Melissa Mark-Viverito. "Ken Thompson didn't just uphold the law -- he made it more fair for all Brooklynites."

Thompson is survived by a wife and two children. Details on funeral services were not immediately available.