North Charleston police officer Michael Slager is seen allegedly shooting 50-year-old Walter Scott in the back as he runs away in this still image from video in North Charleston, S.C., taken Saturday. NBC News identified the witness who filmed the shooting as Feidin Santana. Reuters

The anonymous eyewitness who filmed the fatal shooting of Walter Scott in South Carolina last weekend has been identified as Feidin Santana. NBC News interviewed Santana on Wednesday about the events that led to Scott's death and officer Michael Slager's arrest.

Santana told NBC News that he pushed record when heard a Taser. "I knew right away I had something on my hands," he said.

Santana's video of the incident went viral Tuesday and has been hailed by many as the reason Slager has been indicted for murder. The Scott family attorney, L. Chris Stewart, called Santana a hero. "We have to really recognize the strength and fortitude and fearlessness that it took to come forward when you know you just filmed a police officer murder somebody,” Stewart said, according to the Guardian. “That’s the kind of person that needs to be duplicated."

Santana has been working with state investigators who are looking into Scott's death. Scott, an black unarmed 50-year-old, was killed Saturday in North Charleston, S.C. after running from Slager during a routine traffic stop. Slager said he felt threatened. Santana's video shows the officer switching a Taser for a Glock pistol and shooting at the suspect eight times. The Guardian reported that Santana can be heard on tape swearing after Slager opens fire.

Santana took the video and sent it to the Post and Courier, which posted the recording on Tuesday. The New York Times edited the clip and used it that night, according to U.S. News and World Report. “What if there was no video? What if there was no witness? Where would we be without that video?” attorney Justin Bamberg asked at a news conference. He added, “If there was no video, I do not believe that officer would be in jail."

Internet users Wednesday drew comparisons between Santana and Ramsey Orta, who filmed as a New York officer choked unarmed black man Eric Garner last year. Orta, 23, has said he feels targeted by police for releasing the footage. The Daily Beast reported recently that Orta is afraid to eat the food in jail for fear it's poisoned.

Many Twitter users who posted praise for Santana expressed concern about his safety.