Prosecutors dropped the remaining charges Wednesday against three Baltimore police officers awaiting trial in the death of Freddie Gray, ending the case without any convictions.

Gray was a 25-year-old black man whose neck was broken while he was handcuffed and shackled but left unrestrained in the back of a police van in April 2015. His death added fuel to the growing Black Lives Matter movement, set off massive protests in the city and led to the worst riots the city had seen in decades.

The day started with a pretrial hearing for Officer Garrett Miller -- who had faced assault, misconduct in office and reckless endangerment charges. 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 rest of the officers.

The decision by prosecutors comes after a judge had already acquitted three of the six officers charged in the case, including the van driver who the state 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.

The case led the police department to overhaul its use of force policy, and all officers will soon be equipped with body-worn cameras. The U.S. Justice Department has also launched an investigation into allegations of widespread abuse and unlawful arrests by the department, and the officers have sued State's Attorney Marilyn Mosby, saying she intentionally filed false charges against them.

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

A defiant Mosby held a news conference shortly after the announcement, saying there was "a reluctance" and "an obvious bias" among some officers investigating the case.

"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.

Police Commissioner Kevin Davis released a statement saying the decision "will help move our City forward."

Ivan Bates, an attorney for Sgt. Alicia White, said everyone wanted to know what happened to Gray.

"The Baltimore city police, they did the investigation and they said it was an accident," he said. "The Baltimore state's attorney had the opportunity to do an investigation and they did not. It is the Baltimore city state's attorney's office that denied justice to the Gray family and to these officers."

Gene Ryan, president of the Fraternal Order of Police Lodge 3, said justice was served. He argued that the detectives in the case did a thorough job and he called the state's attorney's comments "outrageous" and untrue.

Gray's mother, Gloria Darden, stood by Mosby, saying police "lied, I know they lied, and they killed him."

Attorneys for the officers planned a news conference later Wednesday. Officers worried Mosby's statement would incite violence against them, a police source told Fox News, saying "she really blasted us."

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

Mosby wasted little time in announcing charges after Gray's death -- one day after receiving the police department's investigation while a tense city was still under curfew -- and she did not shy from the spotlight. She posed for magazine photos, sat for TV interviews and even appeared onstage at a Prince concert in Gray's honor.

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

Many feared that the acquittals could prompt more protests and unrest, but that never panned out and the streets appeared mostly calm Wednesday.

Three of the officers who were charged are white and three are black. The victim, judge, top prosecutor and mayor are 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 and her husband, Nick Mosby, a councilman for Baltimore's west side who announced his mayoral candidacy shortly after Rawlings-Blake 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 bore witness to an inherent bias that is a direct result of when police police themselves," she said.

Fox News' Guerin Hays, Leland Vittert and The Associated Press contributed to this report.