The city of Baltimore braced for a verdict as closing arguments were made Monday in the first of six trials of police officers charged in the death of Freddie Gray.

Mayor Stephanie Rawlings-Blake said business should continue as usual and that people must respect the jury’s decision, but the city also opened an emergency operations center as a precaution to help authorities coordinate any necessary response.

Prosecutors described Officer William Porter as indifferent to Gray’s safety, repeatedly denying him medical care in the police wagon where his neck was broken after he was left handcuffed and shackled but unbuckled, and thus vulnerable to being bounced around inside the metal compartment.

The wagon “became his casket on wheels” after Porter failed to belt him to the bench or call for a medic after he was injured, prosecutor Janice Bledsoe said.

“With great power comes great responsibility,” Bledsoe said. “Porter had the opportunity on four or five occasions to wield his power to save Freddie Gray. He abused his power. He failed his responsibility.”

Defense closings were expected following a short break.

Porter, who is charged with manslaughter, assault, misconduct in office and reckless endangerment, testified that he did nothing wrong to Gray, who was arrested after running from officers in his neighborhood. He could face about 25 years in prison if convicted on all charges.

The mayor said in a letter to community leaders that she has “no doubt” city officials are prepared for anything, and that the city also is communicating with outside law enforcement agency partners.

Demonstrations were initially peaceful following the young black man’s death on April 19, a week after his arrest. But unrest broke out on the day of his funeral, bringing a curfew and the National Guard to the streets, and fueling the “Black Lives Matter” movement that has increased scrutiny of how police treat minorities.

In Porter’s case, an officer’s negligence, rather than any violent act or excessive force, is in question. In American jurisprudence, with no eyewitnesses telling what happened inside the van and no unequivocal evidence showing exactly when his neck was broken, legal experts have said this could be difficult to prove.

Prosecutors said Porter is partly responsible because he ignored a departmental policy requiring officers to buckle prisoners in seat belts, and didn’t call for an ambulance when Gray indicated he needed medical aid.

Porter, who lifted Gray off the van floor and sat him on the seat at one point during the trip to the police station, told jurors he didn’t call a medic because Gray didn’t show signs of injury, pain or distress and said only “yes” when he asked if he’d like to go to the hospital.

Porter said he told van driver Caesar Goodson to take him there, because while he still didn’t believe Gray was really hurt, he knew the jail would reject a prisoner claiming injury. He told investigators that Gray had been kicking inside the van at a previous stop, and “he didn’t appear hurt in any way, shape or form.”

Other witnesses also testified that Goodson was responsible for buckling Gray to the bench. He faces the most serious charge: second-degree “depraved-heart” murder.

Porter’s fate may influence the trials of the other officers and set the tone for the city’s healing.

With that in mind, Baltimore Police Commissioner Kevin Davis canceled leave for all officers through Friday, saying “the community has an expectation for us to be prepared for a variety of scenarios.”

The mayor has urged residents to remain calm.

“Whatever the verdict, we need everyone in our city to respect the judicial process,” Rawlings-Blake said. “We need everyone visiting our city to respect Baltimore.”

(AP)