BALTIMORE (AP) -- Prosecutors failed for the second time in their bid to hold Baltimore police accountable for the arrest and death of Freddie Gray when an officer was acquitted Monday in the racially charged case that triggered riots a year ago.

A judge cleared Officer Edward Nero of assault, reckless endangerment and misconduct, concluding that Nero played little role in Gray's arrest and wasn't responsible for the failure to buckle the black man into the police van where he suffered a broken neck.

Upon hearing the verdict, Nero hugged his attorney and appeared to wipe away a tear.

Nero, who is white, was the second of six officers charged in the case to stand trial. The manslaughter case against Officer William Porter ended in a mistrial in December when the jury deadlocked. Prosecutors plan to retry him in September.

Nero's lawyers said he and his wife and family are "elated that this nightmare is finally over."

"The state's attorney for Baltimore City rushed to charge him, as well as the other five officers, completely disregarding the facts of the case and the applicable law," they said in a statement.

Prosecutors had no comment; they are under a gag order.

Trial No. 3 - that of van driver Caesar Goodson, who prosecutors believe is most culpable in Gray's death - is set to begin in two weeks. He is charged with second-degree murder.

David Weinstein, a Florida attorney and former federal civil rights prosecutor who has been following the case, said the verdict will probably serve as a "wake-up call" for prosecutors.

"This speaks to the notion a lot of people had when this first happened, which is that it was a rush to judgment," Weinstein said. "The state's attorney was trying to balance what she had with the public outcry and call to action given the climate in Baltimore and across the U.S. concerning policing, and I think she was overreaching."

Gray died a week after suffering a spinal injury in the back of the van while he was handcuffed and shackled but not belted in.

His death set off looting and arson that prompted authorities to declare a citywide curfew and call out the National Guard to quell unrest in Baltimore for the first time since the riots that erupted in 1968 over the assassination of the Rev. Martin Luther King Jr.

Gray's name became a rallying cry in the growing furor over the deaths of black men in clashes with police.

Nero, 30, waived his right to a jury trial, choosing instead to let Circuit Judge Barry Williams decide his fate. The assault charge alone carried up to 10 years in prison.

"The state's theory has been one of recklessness and negligence," the judge said in his ruling . "There has been no evidence that the defendant intended for a crime to occur."

Nero remains on desk duty and still faces a departmental investigation that could result in disciplinary action.

About a dozen protesters gathered outside the courthouse as the verdict was read, but they were far outnumbered by members of the media.

Mayor Stephanie Rawlings-Blake noted the departmental review and pleaded for calm.

"We once again ask the citizens to be patient and to allow the entire process to come to a conclusion," she said. "In the case of any disturbance in the city, we are prepared to respond. We will protect our neighborhoods, our businesses and the people of our city."

Gray's family settled with the city for $6.4 million in September. An attorney for the family, Billy Murphy, said they respected the verdict, and he commended the judge for resisting "enormous pressure" and showing "tremendous courage in ruling against public opinion."

Some legal experts said the judge's ruling was so narrowly tailored - and the facts so different from those of the other defendants - that it provides little guidance to what could happen in the upcoming trials.

Baltimore defense attorney Warren Alperstein, who watched the trial, said Nero wisely elected a non-jury trial, because a judge is more capable of applying the complex constitutional questions involving what is a proper arrest.

The van driver, though, should put his fate in the hands of a jury, because "when you're facing a murder charge, as Goodson is, you do not want to put all your eggs in one basket," Alperstein said.

On the morning of April 12, 2015, Lt. Brian Rice was on patrol in a high-crime neighborhood when he made eye contact with Gray and Gray ran away. Rice called for backup, and Nero and Officer Garrett Miller responded.

According to testimony, Miller jumped off his bicycle, caught up with Gray and put him in handcuffs. Gray was placed in the back of the van, seated on the bench.

A few blocks away the van stopped, and Rice and Miller took Gray, who police said had been kicking, screaming and shaking the van, out of the wagon, placed him in leg irons and replaced his metal cuffs with plastic ones. The officers, with Nero's help, loaded Gray back into the van, sliding him in his belly, head-first.

Nero's attorneys said Nero touched Gray only twice - first to help him up from the ground after he had been handcuffed and was asking for an inhaler, then to help put him back in the van.

After Gray was taken into custody, police found a knife on him. But the judge did not allow testimony about that.

Prosecutors argued that police had no probable cause to arrest Gray. But the judge said that Nero was not involved in the arrest, so the question of whether it was improper was irrelevant.

Tessa Hill-Aston, president of the Baltimore chapter of the NAACP, said officers' failure to see that Gray was buckled in "speaks to a lack of training."

"That's where the system failed Freddie. Because everyone is passing the buck on who is supposed to strap him in," she said

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