LOUISVILLE, Ky. (AP) -- A Baltimore judge says there is a hung jury in the case of a police officer charged in the death of Freddie Gray.

The mayor of Baltimore is calling for respect and unity after a mistrial was declared in the trial of an officer charged in the death of Freddie Gray.

Baltimore Mayor Stephanie Rawlings-Blake says "as a unified city, we must respect the outcome of the judicial process." She says in the case of any disturbance in the city, authorities are prepared to respond.

Upon learning of the mistrial, protesters chanted "no justice, no peace" outside the courthouse.

After court adjourned, Officer William Porter conferred solemnly with defense attorney Joseph Murtha and walked from the courtroom. A female supporter joined Porter on a marble bench in a corner of the hallway. Courthouse deputies blocked reporters from approaching them.

Murtha declined comment, citing a judicial gag order. Baltimore City State's Attorney Marilyn Mosby, who brought charges against six officers in the arrest and death of Gray, also declined comment.

Circuit Judge Barry Williams announced Wednesday that the jury couldn't reach its decision after three days of deliberations in the manslaughter trial of William Porter.

He was the first of six officers to stand trial on charges stemming from Gray's arrest and death. The judge told the jurors they had "clearly been diligent" before he dismissed them.

As the decision was announced a handful of protesters gathered outside the courthouse.

Jurors deliberating the fate of an officer charged in the death of Freddie Gray had asked the judge for a copy of a transcript from a witness, but the judge had refused to give it to them.

The jury made the request Wednesday during the panel's third day of deliberations in the trial of Officer William Porter, who faces manslaughter, assault, reckless endangerment and misconduct charges.

Jurors told the judge Tuesday afternoon that they were deadlocked, but Circuit Judge Barry Williams told them to keep working.

The jurors have made several requests since they began deliberating Monday. The judge has granted some of them and refused others, saying they were not part of the evidence.

It's not clear exactly what witness transcript they were seeking Wednesday.

Gray died after suffering a broken neck in a police van while handcuffed and shackled. An autopsy concluded his head was probably slammed against inside the van as the van turned a corner or stopped.

Prosecutors say Porter should have called an ambulance when Gray indicated he needed medical help, and should have buckled Gray's seat belt.

Porter testified Gray didn't seem hurt. He says he told the driver and a supervisor Gray wanted to go to a hospital.

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