Six Baltimore police officers are charged in the death and arrest of Freddie Gray. Here’s who they are. (Claritza Jimenez,Erin Patrick O'Connor/The Washington Post)

Prosecutors said Thursday that Freddie Gray suffered his severe neck injury during a “rough ride” in a police van, with an officer driving carelessly while Gray was tossed around in the back.

The theory outlined at the start of the trial of Officer Caesar Goodson Jr. marks the first time prosecutors have alleged that Gray was given a “rough ride” the day of his April 2015 arrest.

Prosecutors contended in their opening statement that Goodson was reckless and caused Gray’s injury — and ultimately his death — by failing to put the 25-year-old in a seat belt and by not getting him immediate medical attention as he was taken to jail.

“He was injured because of the way officers transported him — shackled and restrained,” Chief Deputy State’s Attorney Michael Schatzow said. There was no good reason to avoid buckling Gray into the van “except to bounce him around for causing a scene.”

Defense attorney Andrew Graham countered that his client was a hardworking police officer and a good driver, adding that there was no evidence of a “rough ride.”

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Goodson, one of six officers charged in Gray’s arrest and death, is the only one to face a murder charge. In addition to second-degree depraved-heart murder, which carries a maximum 30-year prison sentence, Goodson is charged with manslaughter, assault, misconduct in office and reckless endangerment.

His trial was briefly delayed because of a morning hearing during which Judge Barry G. Williams ruled that prosecutors had not turned over evidence that could have helped the defense.

Williams concluded that prosecutors violated discovery rules by failing to tell defense attorneys about a meeting they had with Donta Allen, the only other arrestee in the police van with Gray. Allen’s testimony could be important because he could offer insight into when Gray was gravely hurt and what officers could have known about Gray’s condition.

Allen initially told police in April 2015 that he believed he heard Gray banging himself inside the van, according to police documents. Allen later told The Washington Post and other media outlets that his statement had been mischaracterized, and that he never said Gray was harming himself.

Prosecutors conducted a follow-up interview with Allen and his attorney in May 2015, but they didn’t take notes during the meeting or disclose to defense attorneys that it had occurred.

Allen’s attorney alerted lawyers representing officers to the meeting last Friday.

Schatzow said his office didn’t disclose the meeting with Allen because he didn’t say anything during the session that wasn’t already provided to the defense. He added that the meeting was “so silly” and “bizarre” that prosecutors couldn’t take it seriously enough to take notes.

But Graham said it’s not up to prosecutors to decide whether the information is relevant. Williams agreed and said the meeting with Allen — who is lined up as a defense witness — should have been disclosed.

The judge sternly admonished prosecutors, saying they clearly didn’t understand what represents important evidence that they are obligated to turn over. The judge added that it was the third such time prosecutors have failed to turn over evidence to benefit the defense.

“Isn’t that your duty, council? To turn things over?” Williams asked. “What else is out there that you didn’t turn over?”

Despite the violation, Williams did not dismiss the charges against Goodson outright. Instead, he gave prosecutors until Monday morning to turn over any additional evidence relevant for the defense and said he would not hesitate to issue sanctions as needed.

In his opening statement, Graham said his client faces “the most aggressive and most unfair” of the charges placed against officers in the case. He said Goodson did not act with any malice or a “depraved heart” as prosecutors contend.

Gray had been arrested before and was known to resist, Graham said. He said officers didn’t seat-belt Gray because he was “wildly combative,” and that there was no evidence to show Gray was visibly injured before the van’s final stop.

Goodson was such a good driver that “one could fall asleep in the back of his van,” Graham said.

Prosecutors, however, contend that at some point, Goodson — who “had the ultimate responsibility for the safety of Mr. Gray” — sped through a stop sign and made a hard right turn. The van swung through the turn so fast it went into the lane of oncoming traffic, Schatzow said.

“A seat belt would have prevented Mr. Gray’s injury,” Schatzow said. “Prompt medical attention would have saved his life.”

Gray was arrested April 12, 2015, after making eye contact with police in his West Baltimore neighborhood and then running. After officers detained Gray, they loaded him into the back of a police van with his arms and legs shackled. On the way to jail, the van made a series of stops and Gray sustained a serious spinal injury. He died one week later.

Goodson is the third officer to go to trial in the high-profile case, which ignited protests and unrest in Baltimore. In December, the trial of Officer William G. Porter ended in a hung jury. Last month, Edward Nero — who chose a trial by judge instead of jury — was acquitted.

Goodson has also selected a bench trial, waiving his right to a jury.

Seven prosecution witnesses were called during the first day of testimony. Many were members of the Baltimore police who spoke about the department’s policies and officer training related to prisoner safety and buckling detainees into vans.

The trial resumes Friday morning.