BALTIMORE — 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 Gray was given ill treatment 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 seatbelt.

‘‘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 hard-working police officer and good driver, and said there was no evidence of a ‘‘rough ride.’’

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, and misconduct in office.

His trial was briefly delayed because of a morning hearing that resulted in a ruling by Judge Barry G. Williams that prosecutors had failed to turn over evidence that could have helped defense attorneys representing the officers.

Williams concluded that prosecutors committed a discovery violation by failing to tell defense attorneys about a meeting they had with Donte Allan, the only other arrestee in the police van with Gray. Allan’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 be 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.

Williams did not dismiss the case against Goodson outright as the defense requested as a result of the violation, but did give prosecutors until Monday morning to turn over any additional evidence they deem could help the defense.