A police officer was just found not guilty of all charges surrounding a black man's death that sparked riots across Baltimore

A Baltimore police officer charged in the arrest and death of Freddie Gray was found not guilty on all charges on Monday morning, the Associated Press reported.

Gray died after suffering spinal injuries he is believed to have sustained in a police van following his arrest in April of last year.

Edward Nero, one of Gray's arresting officers on trial, was facing the possibility of over 15 years in prison, Fox DC reports.

Nero, who did not testify, pleaded not guilty to misdemeanor charges of second-degree assault, reckless endangerment, and two separate charges of misconduct in office.

Baltimore's Mayor Stephanie Rawlings-Blake released a statement following the verdict noting that Nero would still be subject to an administrative review by the Baltimore police:

Today Judge Barry G. Williams found Officer Edward Nero not guilty of all criminal charges. This is our American system of justice and police officers must be afforted the same justice system as every other citizen in this city, state, and country. Now that the criminal case has come to an end, Officer Nero will face an administrative review by the Police Department. We once again ask the citizens to be patient and to allow the entire process to come to a conclusion. 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.

During the trial, prosecutors presented a novel legal theory that Nero didn't have the authority to detain Gray because he didn't have probable cause. If the prosecutors' theory is proven correct, Nero's decision to put Gray in handcuffs constitutes assault.

The Baltimore Sun reported that Judge Barry Williams seemed skeptical of the prosecution's argument.

"Every time there is an arrest without probable cause, it is a crime?" Williams asked Deputy State's Attorney Janice Bledsoe, according to The Sun. When Bledsoe said that the answer depended on the circumstance, Williams said "No, no, no, no" and repeated his question. He returned to the issue again later, noting that arrests "for which the conduct of the officer is not objectively reasonable" have "all the elements of a crime."

The prosecution and defense agreed that nothing leading up to Gray's being handcuffed was illegal and that no assault was committed after Gray was searched. The Sun reported that, in doing so, the prosecution ceded arguments claiming Nero's decision to pursue Gray was wrong. The state argued that Nero's actions in the approximately three minutes prior to the search did constitute an assault since Nero had not attempted to gain information to justify the stop.

The argument goes back to a Supreme Court case from 2000, Illinois v. Wardlow, when the court ruled that cops have a right to stop people for fleeing at the sight of officers as long as other suspicious factors are at play - like being in a high-crime area.

In order to win, the prosecutors effectively claimed that the Supreme Court case ruling is wrong.

"Is it a gutsy theory? Yes. Do I think most prosecutors would have brought charges on this theory? Probably not," Paul Butler, a former federal prosecutor and a Georgetown University law professor, told The Sun.

The defense countered that Nero and other officers' actions were allowed because of the Supreme Court case Terry v. Ohio, which ruled that police can detain people for a short period of time (a "Terry stop") if they have reasonable suspicion that the person has been involved in a crime.

Prosecutors also claimed that the officers failed to secure Gray with a seat belt, as was required by a policy change made only days earlier.

During Nero's trial, Capt. Justin Reynolds, a former training director for the Baltimore police who testified as an expert witness, said that it took two hands to secure a detainee's seat belt, according to The Sun. As a result, he claimed, an officer could not secure the detainee without putting himself at risk. Reynolds admitted that he had seen detainees secured with seat belts in the vans before and that doing so was possible with a cooperative detainee.

On Thursday, the prosecution argued that it was not possible for Nero not to be aware of the potential risk of not securing Gray.

Gray's death came amid a series of high-profile killings of black men by police officers in the US.

Peaceful protests in Baltimore after Gray's death quickly descended into chaos, with the situation growing so violent that the governor of Maryland declared Baltimore to be in a state of emergency and called in the National Guard.

Five other officers have been charged in relation to Gray's arrest and death: William Porter, Caesar Goodman Jr., Garret Miller, Lt. Brian Rice, and Sgt. Alicia White. Goodson, Porter, Rice, and White face manslaughter charges, with Goodson, the van driver, facing an additional second-degree "depraved heart" homicide charge. All face second-degree assault, reckless endangerment charges, and misconduct in office charges. False imprisonment charges initially filed against three of the officers were dropped.

Porter's trial ended in a mistrial with a hung jury in December. His retrial is due in September. The other officers are all due to be tried in coming months.

Gray had come under the suspicion of officers Nero and Miller after he "fled unprovoked upon noticing police presence." During his arrest, police found on Gray what they claimed was an illegal switchblade.

Prosecutors had initially contested that the knife was legal, but the argument was dropped after police cited a city code that they claimed it violated. Prosecutors then argued that police had not been aware of the knife when they detained Gray.

According to The Sun, however, the knife did not come up during testimony.