Walter Scott Shooting Witness: 'Hard to See' Mistrial for Michael Slager

— -- Feidin Santana, the witness who recorded video of the fatal Walter Scott shooting, told ABC News he feels it was "hard to see" a mistrial for former police officer Michael Slager.

The mistrial was announced Monday after jury members said they were unable to come to a unanimous decision in Slager's state murder trial. They had deliberated since closing arguments ended last Wednesday.

Slager, who is white, was accused of killing Scott, an unarmed black man, at a traffic stop on April 4, 2015, in North Charleston, South Carolina, when Slager was a North Charleston Police Department officer. Witness video shot from Santana's cell phone surfaced shortly afterward and appeared to show the moment Slager fatally shot Scott as he ran away. The video garnered national attention, propelling Slager into the spotlight. Slager was fired from the force after the shooting, according to The Associated Press.

Slager had pleaded not guilty to murder.

Santana told ABC News that for him, "it was hard to see" this outcome with "the case as clear as it is, with this type of evidence."

"It's not a loss, but also it's not a victory for justice," he said. "And you ask yourself, what if there was no video? What if I wasn't there? Would we have gotten this far in this trial?

"It's hard sometimes," Santana added. "That's the way justice is over here and we have to understand it. But it's a little bit disappointing."

After the mistrial was announced, Solicitor Scarlett Wilson vowed she would seek a retrial. Slager also faces a federal trial, which is scheduled for next year.

Santana was called to testify by the prosecution last month, telling the court of the moments before, during and after he witnessed the deadly shooting.

Santana told the court how he first saw Scott running and Slager running after him. Santana said he later saw Scott on the ground and heard an "electric sound" and said he decided to approach the scene and start recording.

"It was a lot of movement from both men," Santana said. "I continued hearing the electric sound as I was approaching to the fence. They were moving a lot. The black man ... he just tried to get away from the Taser that I was hearing. But I didn't know [at the time] that it was a Taser -- I just knew that it was something electric sound."

Santana said the officer's left hand was trying to control Scott and the officer was on top of him.

Then both men stood up, Santana said, and he saw "the black man trying to get away and the officer trying to control the person."

"Both men get up very quick," Santana said in court. He said the officer was holding onto Scott but Scott was able to break away.

"After he got away ... it's been something that I didn't expect," Santana said. "[The officer] shoot the man running from him. And he shoot until he gets on the ground."

In court, defense attorney Andy Savage said Slager shot Scott because he was in fear for his life. Savage added that Slager didn't know what Scott would do and said Scott could have hurt someone if he got away.

ABC News' Brandon Baur and Katie Conway contributed to this report.