In a special election on December 12, 2017, Alabama chose Democrat Doug Jones over Republican and alleged sexual predator Roy Moore. Jones will now head to the U.S. Senate, bringing to a close an election that drew national and international attention—unusual for a state election, but even more so for Alabama.

Much of the media attention on Jones, the first Democrat elected in the state in a quarter century, focused on his role in prosecuting Ku Klux Klan members who had planted a bomb that killed four girls at a black church.

The terrorist attack occurred on September 15, 1963, when a bomb went off at the 16th Street Baptist Church in Birmingham, Alabama. The church was a known meeting place for Civil Rights organizers, and was targeted for that reason. The bomb injured at least 20 people and killed four young girls: Addie Mae Collins, Cynthia Wesley, Carole Robertson, and Carol Denise McNair.

According to Glenn D. Brasher, a history professor at the University of Alabama, the FBI determined that four KKK members had planted the bomb. FBI agents, then led by Director J. Edgar Hoover, knew the attackers’ names, and had even made secret recordings to prove it.

However, “the FBI under Hoover sealed those files away, because J. Edgar Hoover was not exactly a proponent of the civil rights movement,” Brasher says.

By doing this, Hoover ensured that a court could not use them as evidence to prosecute the attackers, making it more difficult to convict. For 14 years after the bombing, none of the men were prosecuted for their crime. The first one to be arrested (and convicted) was Robert Edward Chambliss in 1977—whose trial a young Doug Jones attended when he was in law school.

Chambliss “was prosecuted largely on circumstantial evidence,” Brasher says. “The prosecution didn’t have access to all of the information that the FBI had collected immediately after the attack in the ‘60s.” Nevertheless, the overwhelming circumstantial evidence let to a conviction.

Although Jones was only a boy himself when the bombing happened, the government didn’t release the FBI’s evidence against these men for decades. By the time the government finally declassified the these files, Jones had been appointed a U.S. Attorney for the Northern District of Alabama by President Bill Clinton, and was able to prosecute the case.

This was in the late 1990s, after one of the attackers, Herman Frank Cash, had already died. But two of the men were still alive, and Jones realized he had the chance to continue the work of that trial from over 20 years ago. Using the newly revealed evidence, Jones successfully prosecuted two more of the attackers that the FBI had identified: Thomas Edwin Blanton Jr., convicted in 2001; and Bobby Frank Cherry, convicted in 2002.

According to Sharony A. Green, a professor of history at the University of Alabama, Jones’ victory is particularly significant given the state’s racial politics: Jones, a man who made his name prosecuting the KKK, beat an opponent who, when asked when American was last “great,” replied: “I think it was great at the time when families were united, even though we had slavery.”

“People knew how enormous the results, the outcomes of yesterday’s election, would be for Alabama,” Green says. “You had folks who probably wanted to vote for a Republican, but instead voted for someone who was better aligned with some of their values.”