Deadlocked jurors go back to work in trial of Baltimore cop charged in Freddie Gray's death
Baltimore Police officer William Porter approaches the court House in Baltimore, Maryland, November 30, 2015. (REUTERS/Patrick Samansky/Pool)

A deadlocked Maryland jury will try again on Wednesday to reach a decision in the trial of a Baltimore police officer charged in the April death of black detainee Freddie Gray.

Officer William Porter, 26, is on trial for involuntary manslaughter and other charges in Baltimore City Circuit Court. The jury said on Tuesday that it was unable to reach a decision after almost 10 hours of deliberations in the high-profile case.

Judge Barry Williams ordered the jury of seven women and five men to keep deliberating. He did not say how the jury was stymied.

Porter is the first of six officers to be tried in Gray's death from a broken neck sustained in the back of a police van.

His death triggered protests, rioting and arson in the majority black city of 620,000 people and intensified a U.S. debate on police treatment of minorities.

Three of the six officers charged in Gray's death, including Porter, are black. Charges against the other officers range from second-degree murder for the van's driver, to misconduct.

Porter is also charged with second-degree assault, reckless endangerment and misconduct in office.

Gray, 25, was arrested after fleeing from police. He was put in a transport van, shackled and handcuffed, but was not secured by a seat belt despite department policy to do so. Gray died a week later.

Porter, who was a backup officer, testified that Gray told him he needed medical aid. Porter told the van's driver and a supervisor that Gray had asked for aid but none was summoned, according to testimony.

The defense has argued that Porter did not believe Gray was seriously injured until the van's final stop. His lawyers have said that Porter acted as any reasonable officer would have.

Prosecutors contend that Porter was criminally negligent in ignoring Gray's pleas for medical aid and in failing to secure him in the van.

(Reporting by Ian Simpson and Donna Owens; Editing by Frances Kerry and Dan Grebler)