The Baltimore police van Freddie Gray was transported in the day of his arrest and injury is moved to the Courthouse East garage prior to being shown to jurors in the trial of officer William Porter on Thursday, Dec. 3, 2015 in Baltimore.  Jurors did not ask any questions about the van when they inspected it, and were not given any information about it during the viewing, Baltimore Circuit Judge Barry Williams said. Reporters and members of the public were not allowed to witness the jurors' viewing. (Ian Duncan/The Baltimore Sun via AP)  WASHINGTON EXAMINER OUT; MANDATORY CREDIT

The Baltimore police van Freddie Gray was transported in the day of his arrest and injury is moved to the Courthouse East garage prior to being shown to jurors in the trial of officer William Porter on Thursday, Dec. 3, 2015 in Baltimore. Jurors did not ask any questions about the van when they inspected it, and were not given any information about it during the viewing, Baltimore Circuit Judge Barry Williams said. Reporters and members of the public were not allowed to witness the jurors’ viewing. (Ian Duncan/The Baltimore Sun via AP)

Officer William Porter was poised and calm as he testified in his own defense on Dec. 9, telling jurors that he didn’t call an ambulance for Freddie Gray because the man was alert, appeared uninjured and didn’t complain of any pain or wounds in the back of a police van.

Instead, Gray only said “yes” when Porter offered to get him medical aid, the officer testified. Porter said he did tell his colleague, the van driver, to take Gray to the hospital after the man said he needed medical attention.

Porter, a patrolman, responded to calls for assistance at some of the van stops. During the fourth stop, Porter went inside the back of the van and lifted Gray, who was handcuffed and shackled, from the floor onto the bench.

The fourth stop is crucial in Porter’s case because prosecutors say Gray was already injured by the time he arrived there, and Porter’s failure to call a medic to the scene contributed the Gray’s death. Defense attorneys say Gray was injured later in the ride.

Prosecutors also say by not buckling Gray into a seat belt during that stop, Porter was criminally negligent. The department requires detainees to be buckled up and the policy was updated just days before Gray’s arrest, leaving no ambiguity about whether a prisoner should be belted in.

As Porter spoke, jurors listened intently, some leaning forward and scribbling notes as he spoke.

Porter, the first of six officers to go on trial, said he only realized Gray was hurt when the van reached the police station. Porter said Gray was unresponsive “with mucus around his nose and mouth.”

He called Gray’s name — as he’d done at previous stops, which elicited responses — but this time Gray was silent. Porter told jurors the experience was “a very traumatic thing for me.”

Porter faces manslaughter, assault, misconduct in office and reckless endangerment charges. If convicted on all of the charges, the maximum penalty he faces is about 25 years.

Defense attorneys have suggested that the van driver was responsible for Gray’s safety and indicated the officer may have thought Gray was faking an injury to avoid going to jail.

Porter said during the fourth stop, Gray made eye contact with him and spoke “in a regular tone of voice.”

“He never made a complaint of pain or an injury,” Porter said. “In order to call for an ambo I need age, sex, location and complaint of injury. He wouldn’t give me a complaint of injury.”

Gray was a 25-year-old Black man who died a week after suffering a spinal injury at some point during a 45-minute ride in the back of the van. His death set off protests and a riot in the city, and became a rallying cry for the Black Lives Matter movement.

Porter, who is also Black, told jurors that when Gray was arrested, he overheard him screaming and mentioning something about needing an inhaler. When asked if Gray said he couldn’t breathe at the van’s fourth stop, Porter said, “absolutely not.”

One of the prosecution’s witnesses, an internal affairs investigator, said Porter told her that Gray said during the van’s journey that he couldn’t breathe. But Porter explained on Dec. 9 that the investigator was mistaken, and he only heard Gray say that when he was arrested, not when he was in the van.

As for why he didn’t buckle Gray into a seat belt, Porter told the jury that the wagon is “pretty tight” and said that of his 200 arrests involving the transport van, he has never belted in a prisoner.

Porter added that he left the scene after lifting Gray from the floor of the wagon to the bench, and it was Caesar Goodson, the driver, who closed the wagon’s doors.

It would have been his responsibility, Porter said, to buckle Gray into a seatbelt and he didn’t know if he did.

Goodson faces the most serious charge stemming from Gray’s death: second-degree “depraved-heart” murder. His trial is next month.