Hours after she received the autopsy report on Freddie Gray, who suffered a fatal spinal cord injury in police custody, Baltimore State’s Attorney Marilyn Mosby announced charges against six officers.

“To the people of Baltimore and the demonstrators across America, I heard your call for ‘no justice, no peace,’ ” she told a community roiled by protests in May 2015. “Your peace is sincerely needed as I work to deliver justice on behalf of this young man, those that are angry or hurt or have their own experience of injustice.”

On Wednesday, Mosby surrendered to the “dismal likelihood” that she would not obtain a single conviction. One officer’s trial already had ended in a hung jury and three other officers had been acquitted. Instead of going forward with another trial scheduled for this week, Mosby dropped all remaining charges. “We could try this case 100 times, and cases like it, and would end up with the same result,” she said.

What went wrong?  Mosby blamed the criminal justice system, the judge, the lack of community oversight of the Baltimore Police Department. She didn’t consider that her own rush to judgment might have poisoned the prosecution.

She had bypassed a grand jury, announcing she’d found probable cause herself, and filed charges 12 days after Gray’s death. Four of the officers were charged with homicide counts, ranging from involuntary manslaughter to second-degree murder.

Nothing stuck. Nothing.

The truth is that Mosby, an ambitious rookie prosecutor, overreached and overpromised.

The officers were accused of arresting Gray for no good reason, roughing him up, throwing him in the back of a police wagon without a seat belt and ignoring his pleas for medical attention as he bounced around on the way to the police station. He died a week later.

It happened against a growing nationwide outcry over police violence, especially toward black men.

Chicagoans know all too well what it’s like to stand in that storm. Chicago is working to overhaul a police disciplinary system that has failed for decades to identify and punish abusive cops. The U.S. Department of Justice is conducting a civil rights investigation. It all came about after a judge ordered the release of a video that shows a white police officer shooting a black teenager in the back and continuing to fire at his crumpled body.

No one could accuse Cook County State’s Attorney Anita Alvarez of rushing to file charges in that case. It took her more than a year — and it led to her defeat in the March primary election. Angry voters were convinced Alvarez did not want to prosecute a police officer. They rejected her explanation that she was simply conducting a thorough investigation.

Two years earlier, Mosby unseated the incumbent Baltimore state’s attorney by promising to crack down on police misconduct. A Baltimore Sun investigation that year found that over four years, more than 100 people had won court judgments or settlements arising from claims of police brutality or civil rights violations — costing taxpayers millions. The ACLU of Maryland found that in the same period, fewer than 2 percent of police-involved killings resulted in charges against an officer.

Mosby was under intense pressure to hold someone accountable for Gray’s death. But her job was to try the officers, not the system. In her haste, she forgot about due process and failed to assemble evidence to prove guilt beyond a reasonable doubt.