BALTIMORE (AP) — Prosecutors on Wednesday dropped all remaining charges against the three Baltimore police officers who were still awaiting trial in Freddie Gray‘s death, blaming police for a biased investigation that failed to produce a single conviction.

The decision means that no one will be held criminally responsible for the death of Gray, a 25-year-old black man whose neck was broken while he was unrestrained in the back of a police van in April 2015.

A judge had already acquitted three other officers, including the van driver who prosecutors considered the most responsible and another officer who was the highest-ranking of the group. A mistrial was declared for a fourth officer when a jury deadlocked.

Gray’s death added fuel to the growing Black Lives Matter movement, set off massive protests in the city and led to the worst riots that Baltimore had seen in decades.

The case also led the police department to overhaul its use-of-force policy. All officers will soon be equipped with body-worn cameras, and the U.S. Justice Department has launched an investigation into allegations of widespread abuse and unlawful arrests by police.

Shortly after the announcement that charges would be dropped, a defiant State’s Attorney Marilyn Mosby held a news conference, saying there was “a reluctance” and “an obvious bias” among some officers investigating Gray’s death.

“We do not believe Freddie Gray killed himself,” she said, standing in the neighborhood where Gray was arrested, a mural of him on a wall over her shoulder. “We stand by the medical examiner’s determination that Freddie Gray’s death was a homicide.”

She walked up to the podium as people chanted “we’re with you,” and her remarks were punctuated by shouts of support.

Gray’s mother, Gloria Darden, stood by Mosby, saying police lied. “I know they lied, and they killed him,” she said.

Attorneys for the officers planned a news conference later Wednesday. They have sued Mosby, saying she intentionally filed false charges against them.

Gray’s family received a $6.4 million settlement from the city.

The day started with a pretrial hearing for officer Garrett Miller, who had faced charges of assault, misconduct and reckless endangerment. But instead of pretrial motions, Chief Deputy State’s Attorney Michael Schatzow told the judge that prosecutors were dropping the charges against Miller and the other officers.

Prosecutors had said Gray was illegally arrested after he ran from a bike patrol officer and that officers failed to buckle Gray into a seat belt or call a medic when he indicated he wanted to go to a hospital. He was handcuffed and shackled when he was hurt.

After Gray’s death, Mosby wasted little time in announcing charges, waiting just one day after receiving the police department’s investigation while a tense city was still under curfew. She did not shy from the spotlight, posing for magazine photos, sitting for TV interviews and even appearing on stage at a Prince concert in Gray’s honor.

The city’s troubles forced Mayor Stephanie Rawlings-Blake to fire her reform-minded police chief and abandon her re-election campaign. She has taken a prominent role on the podium this week at the Democratic National Convention.

Many feared that the acquittals could provoke more protests and unrest, but that never happened, and the streets appeared mostly calm Wednesday.

The Gray case never fit neatly into the narrative of white authorities imposing unfair justice on minorities.

Three of the officers who were charged are white and three are black. The victim, judge, top prosecutor and mayor are all African-American. At the time of Gray’s death, so was the police chief.

No reputations hinged on the case’s outcome as much as Mosby’s and that of her husband, Nick Mosby, a councilman for Baltimore’s west side who announced his mayoral candidacy shortly after Rawlings-Blake left the race. He later pulled out.

Marilyn Mosby spoke so forcefully when she announced the charges against the officers that defense attorneys argued she should recuse herself for bias. She did not let up Wednesday.

“We’ve all borne witness to an inherent bias that is a direct result of when police police themselves,” she said.