BALTIMORE - Police Officer William Porter took the witness stand in his defense Wednesday, giving jurors his account of the day Freddie Gray was fatally injured and casting himself as a well-meaning cop doing his job the best way he knew how.

Porter told jurors he did not call a medic for Gray because Gray "was unable to give me any reason for why he needed one," and that he did not buckle the suspect into a police van because he feared he would have to let Gray too close to his gun.

The officer seemed to suggest a colleague was more responsible for Gray's care, and he talked at length about his own upbringing in the same area Gray called home. He called the moment he found Gray unresponsive "a very traumatic thing for me also," because he knew Gray from his job, and said he was "absolutely" sorry for the death.

The testimony is pivotal, as jurors' impression of Porter will undoubtedly shape whether they find him guilty of involuntary manslaughter.

Porter, 26, is one of six city police officers charged in the case and the first to go on trial. Prosecutors have argued he should be held responsible in the April 12 incident because he failed to properly buckle Gray into a police van and did not get Gray medical attention after the 25-year-old asked for a medic and said, "I can't breathe." Gray died a week later.

When Porter tried to explain why he didn't immediately seek medical attention for Gray, Gray's family members, seated in the courtroom, shook their heads. The officer sparred with Baltimore Chief Deputy State's Attorney Michael Schatzow on cross-examination, especially after Schatzow asked him if the same "no snitching" culture exists among rank-and-file police officers, as Porter testified earlier it did on the streets of Baltimore.

Porter testified that he "saw Gray on a daily routine," and the two had a "mutual respect for each other." But he also said Gray had a reputation for misleading authorities about injury, and said that just two weeks before the April 12 encounter, Gray tried to kick out a window of a police SUV.

Porter testified he did not call for a medic because Gray "was unable to give me any reason for why he needed one."

Porter seemed to cast another officer charged in the case - Caesar Goodson - as bearing more responsibility for handling Gray. Goodson was driving the van in which Gray was being transported and has been charged with second-degree murder in the case.

Porter testified it was understood that a prisoner was under the control of the van driver, and that it would be quicker than calling a medic to let Goodson take Gray to the hospital. Asked by Schatzow why he didn't tell Goodson to drive Gray to the hospital, Porter responded: "There's a hierarchy. I can't tell Officer Goodson what to do."

As for seatbelting Gray, Porter suggested it could have been dangerous.

"That wagon is pretty tight," he said, because the gun on his right hip would have been close to Gray.

"Even the most docile detainee presents a risk," Porter said.