A Baltimore police officer fatally injured black detainee Freddie Gray by giving him a "rough ride" in transport van, a prosecutor said on Thursday in opening statements of the murder trial of a third officer in Gray's death.

A lawyer for Officer Caesar Goodson Jr., 46, said Gray's death in April 2015 was accidental and that Gray caused his own injuries.

"There will be no evidence showing he gave a rough ride or drove improperly," defense attorney Andrew Graham said at the start of what is considered the most high-profile trial in the case.

Goodson drove the police van in which Gray suffered a broken neck. His death triggered protests and rioting in Baltimore and stoked a U.S. debate on police treatment of minorities.

Goodson is accused of second-degree depraved heart murder, the most serious charge against the six officers accused in Gray's death. He also faces manslaughter and other charges.

Prosecutor Michael Schatzow said Goodson bounced Gray around in the van by driving unsafely in retaliation for yelling and kicking the inside of the van. Gray had been arrested for fleeing officers unprovoked in a high-crime area.

Schatzow said Goodson failed to follow procedures when Gray was put in his van while shackled and was not secured with a seat belt.

"There is no good reason for the defendant to fail to seat-belt Mr. Gray," Schatzow told Judge Barry Williams, who is hearing the case in a bench trial.

Schatzow said Goodson had run a stop sign and crossed the street's center line. Goodson also stopped the van at one point and saw that Gray was injured, he said

But Graham said Goodson was a conscientious officer who had driven cautiously. Gray was injured because he thrashed around and stood up in the back of the van, he said.

Before opening statements, Williams had criticized Schatzow and his team for withholding evidence from the defense.

The prosecution had failed to hand over material from a May 2015 interview with Donta Allen, who was put in a separate van compartment after prosecutors contend Gray was injured.

Schatzow told Williams that Allen's comments were similar to what he had said before. Williams said Schatzow would face sanctions and ordered the prosecution to turn over all material to lawyers for Goodson and the four other officers still facing trial.

The trial of one officer in Gray's death ended in a hung jury and Williams issued an acquittal in a second one.