BALTIMORE — After two trials and no convictions, Baltimore’s top prosecutor faces criticism that she moved too quickly to file charges against six officers in the case involving a 25-year-old black man who died a week after he was critically injured in police custody, triggering protests and riots a year ago.

Even the judge overseeing the cases — in his verdict Monday acquitting the latest officer to stand trial in the death of Freddie Gray — said the state failed to prove its case on any of the charges.

Baltimore Circuit Judge Barry Williams acquitted Officer Edward Nero of the assault, misconduct in office and reckless endangerment charges in connection with Gray’s arrest outside a West Baltimore housing complex.