LOS ANGELES — Advocates for criminal justice reform who have elected a wave of progressive prosecutors nationwide captured the crown jewel Friday as former San Francisco District Attorney George Gascon defeated Los Angeles DA Jackie Lacey.

The bitter race to run the nation's largest prosecutor's office was a referendum on reform, but took on greater weight after summer activism over police brutality and racial inequality ignited by George Floyd's death by Minneapolis police.

In an unusual dynamic, Gascon, a former beat cop and police chief, was opposed by law enforcement unions, while Lacey, the first woman and Black person to run the office, was targeted by Black Lives Matter activists.

Gascon had nearly 54% of the 3 million votes counted when an emotional Lacey conceded.

"Our nation is going through a reckoning, and what happened in my election may one day be listed as a consequence of that," Lacey said. "It may be said that one day the results of this election is a result of our season of discontent and a demand to see a tsunami of change."

Gascon, who co-authored statewide criminal justice reforms, promised big changes when he takes office Dec. 7. He pledged not to seek the death penalty or try juveniles as adults. He plans to overhaul a conviction review unit that has only exonerated four people since 2015, and will reopen several cases in which Lacey declined to charge police for killings.

Lacey was seeking a third term on a platform more focused on public safety, though she also highlighted reforms that included a program to treat instead of punish some mentally ill offenders.

She nearly won reelection in a three-way primary in March but fell just shy of the majority needed to avoid a runoff. Gascon, the more moderate of two reform-minded challengers, advanced to the general election with under 30% of the vote.

His message gained traction after activists took to the streets following the death of Floyd, a Black man who cried out that he couldn't breathe as a white Minneapolis officer pinned him to the street in May.

Gascon said he was confident he would have prevailed, but said Floyd's death provided a jolt to his campaign. People he couldn't reach before Floyd's death began returning his calls afterward.

"If we can use these very tragic, horrendous events to change the course of history in this country, I think that we will be honoring their lives," Gascon said Friday.

Since May, protesters across LA rallied to defund police and amplified calls to oust Lacey for failing to prosecute officers in fatal shootings.

Lacey has only brought one manslaughter case against an officer in more than 340 fatal shootings during her two terms. She said the law makes it too difficult to prosecute a police officer in a killing, though she's filed two dozen excessive force cases against officers.

Critics said she was too cozy with police, whose unions provided the vast majority of the $7 million supporting her campaign.

Lacey, who was elected at a time when a prosecutor had to be tough on crime and needed police support, found herself in a new political reality, said Raphael Sonenshein, executive director of the Pat Brown Institute for Public Affairs at California State University, Los Angeles.

"The notion that elected officials went from burnishing their public safety credentials by taking campaign donations from public safety unions and then deciding it would be better not to take that money, that's a change," Sonenshein said. "And it's a rapid change."

Black Lives Matter members demonstrated weekly for three years outside the Hall of Justice, chanting "Jackie Lacey Must Go." They celebrated her imminent departure this week and said they were hopeful Gascon would do better, though they plan to protest if he doesn't.

Gascon plans to meet with members of the group Monday — something Lacey refused to do.

Rahje Branch, a group member, said she was disgusted Lacey had cited the death of Floyd in her concession speech but didn't acknowledge the hundreds killed by law enforcement in LA County. Branch said Lacey's loss was a victory for family members who had been denied justice.

Gascon, who immigrated to LA from Cuba as a teen, was a longtime member of the Los Angeles Police Department before becoming chief in Mesa, Arizona, and then San Francisco, where he was later named DA.

During the campaign, Lacey had criticized Gascon as a failure in San Francisco and said crime would increase in LA if he's elected.

Gascon's $12 million in support swamped Lacey's and came mainly from wealthy donors bent on criminal justice reform. Billionaire George Soros gave $2.25 million. Philanthropist Patty Quillin and her husband, Netflix CEO Reed Hastings, gave over $2 million, according to the Los Angeles Times.

Lacey's campaign was overshadowed the morning before the primary election when her husband pointed a gun at Black Lives Matter protesters who showed up before dawn on the couple's doorstep. David Lacey has pleaded not guilty to three misdemeanor counts of assault.

David Lacey, using a cane, accompanied his wife to the news conference Friday, where she hailed him as her hero for putting his life on the line to protect hers.

The couple kissed through their masks before the news conference and she gave him a hug afterward as they slowly walked out of the room as a scattered crowd of staff and supporters applauded.