Curtis Flowers, a Black Mississippi man whose six trials for the same four murders exposed racial bias in jury selection, has died at 56.

Flowers died Wednesday at his home in Winona, Mississippi, his attorney Rob McDuff told The Associated Press on Thursday. His sister, Priscilla Flowers-Ward, told The New York Times that he had had advanced diabetes. The family is awaiting an autopsy to determine his official cause of death.

How the case against Flowers unfolded

Flowers’ case dates back to July 1996, when four people were killed inside Tardy Furniture, where he had briefly worked before being fired. Prosecutors alleged that Flowers killed the store’s owner and three employees in retaliation for his termination. However, investigators never recovered the murder weapon, and no DNA or fingerprints linked Flowers to the killings, CBS News reported.

District Attorney Doug Evans prosecuted Flowers six times. Four trials resulted in convictions that were later overturned, while two ended in mistrials. Flowers was sentenced to death after his sixth trial in 2010.

The investigative podcast In the Dark began looking into Flowers’ case, examining inconsistencies in the prosecution’s evidence and witness testimony. One witness who had testified that Flowers confessed to the killings later recanted, according to CBS News.

Prosecutors unlawfully excluded Black jurors in Flowers’ trials

In 2019, the U.S. Supreme Court overturned Flowers’ conviction and death sentence, finding that prosecutors had unconstitutionally excluded Black prospective jurors.

Across six trials, Evans struck 41 of 42 Black prospective jurors. Justice Brett Kavanaugh described the prosecution’s efforts as “the State’s relentless, determined effort to rid the jury of Black individuals,” according to The New York Times.

Flowers was released from prison in December 2019 after nearly 23 years behind bars. Mississippi prosecutors dropped all charges against him in September 2020.

“Today, I am finally free from the injustice that left me locked in a box for nearly twenty three years,” Flowers said in a statement obtained by AP. “I’ve been asked if I ever thought this day would come. I have been blessed with a family that never gave up on me and with them by my side, I knew it would.”

In 2021, Mississippi agreed to pay Flowers $500,000 over 10 years in compensation for his wrongful imprisonment.

In addition to his sister, Flowers is survived by his daughter, Crystal Flowers; three grandchildren; his brother, Archie R. Flowers; and his sisters Cora Tyson, Angela Jones and Charita Moore, per The New York Times.