CHARLESTON, S.C. » Jurors at a former policeman’s murder trial today viewed the cellphone video that stunned the nation, showing officer Michael Slager firing eight shots at the back of an unarmed man who was running away.

Slager’s defense team did not want the jury to see the video, made by a bystander who pressed record after spotting the white North Charleston policeman chasing after the black man.

Feidin Santana was already late to work that day in April 2015, but he moved closer and kept recording as Walter Scott wrestled with Slager over the officer’s stun gun. The video shows Scott breaking away until he’s shot from a distance and crumples to the ground.

“For some reason I decided to use my phone to record and prevent something that might happen,” the 25-year-old barber testified. “It was something I will never forget.”

Slager’s defense had sought to keep the video out of the trial, but didn’t object after Santana took the stand. The defense did ask that the jury be instructed that the proper perspective to consider the action would be from the perspective of the officer. They also wanted the judge to prevent the video from being shown in slow-motion.

Judge Clifton Newman denied both requests, saying “I don’t seek to control the manner in which the state presents its evidence.”

Slager, who was fired from the force and charged with murder after the video surfaced, faces 30 years to life if convicted.

Santana testified that he was talking with a friend on his cellphone and walking to work when he suddenly saw a black man running toward him.

“A few seconds later I saw a second person — an officer — chasing the guy,” Santana said. “I froze because I didn’t know what was going on,” he recalled.

Then, as the situation unfolded, he decided to press record and approached a fence around the grassy area where Slager and Scott briefly wrestled on the ground, before Scott broke free and ran.

“I continued hearing an electric sound,” Santana said. Scott “just kept trying to get away from the Taser I was hearing. I didn’t know if it was a Taser. It was just electric.”

The defense says the two men fought over the Taser, but Santana said he never saw it in Scott’s hands, and never saw Scott on top of the officer. He said Scott got away and began running before he was shot down.

Santana also explained why he did not immediately give the video to the North Charleston police.

As a legal permanent resident of the U.S., he said he didn’t want to be caught up in legal proceedings before returning home to the Dominican Republic. Also, he said he initially thought Scott was still alive, so perhaps the video wouldn’t really matter.

He said he told another North Charleston police officer at the scene that he had video of the slaying, and the officer told him he should stay around, but Santana thought better of that. As a biracial man, he said he worried for his own safety in North Charleston in the days after the shooting.

“There were only three people there — Walter Scott, the officer and me,” he said.

Once he learned Scott was dead, Santana said, he reached out to representatives of the Scott family, and it was their attorneys who released it to the media. Later, he turned over his phone to agents from the State Law Enforcement Division.

He said he didn’t know the video would appear everywhere, but once it was, he agreed to interviews and later received royalties that he used to buy a car and help his son and daughter. He also said he paid his own air fare to return to South Carolina for the trial.

On cross-examination, defense attorney Andy Savage questioned Santana, who also is a musician, about some lyrics he wrote months before the shooting, which include the phrase: “Those who must defend us are the worst criminals. Who can I trust?”

Savage asked if that was how he saw things when he made the recording.

“I’m not against any law enforcement, any officer,” Santana replied. “I am against police brutality.”