Jurors in the trial of a Baltimore police officer charged in the death of a black man examined on Thursday the police van in which he suffered his fatal spinal injury.

Officer William Porter, 26, is the first of six officers to go on trial in Baltimore City Circuit Court for the death in April of Freddie Gray. The incident triggered rioting and protests in the largely black city and added fuel to a U.S. debate on police tactics against minorities.

Gray, 25, died a week after he was taken into custody for fleeing an officer and possessing a knife. He suffered a spinal injury in the back of a police transport van that prosecutor Michael Schatzow has likened to that suffered by a diver going into a shallow pool.