State's Attorney Marilyn Mosby, right, holds a news conference near the site where Freddie Gray was arrested after her office dropped the remaining charges against three officers awaiting trial in Gray's death.

BALTIMORE — Fourteen months after the death of a black man whose neck was broken in a police van prompted massive protests, spawned rioting and toppled the careers of Baltimore’s police commissioner and a Democratic mayor poised for re-election, no one will go to jail for the death.

The city’s top prosecutor was righteous in her rage Wednesday as she stood behind a lectern perched at the intersection where Freddie Gray was arrested in April 2015.

Earlier in the day, Baltimore State’s Attorney Marilyn Mosby had dropped the cases against the rest of the six police officers charged in Gray’s death after prosecutors had suffered blow after crippling blow as a judge acquitted three others in rapid succession. Instead of conceding defeat, she blasted the police department for a biased investigation she blamed for failing to secure a single conviction.

“The prosecution of on-duty police officers in this country is surprisingly rare and blatantly wrought with systemic and inherent complications,” the Democratic prosecutor said. “Unlike other cases where prosecutors work closely with the police to investigate what actually occurred, what we realized very early on in this case was that, police investigating police — whether they’re friends or colleagues — was problematic. There was a reluctance and bias that was consistently exemplified.”

Prosecutors alleged the officers involved in his arrest and transport were criminally negligent when they failed to use the seat belt, instead placing Gray on the floor of a prisoner compartment.