(CBS News) A new movie based on a true story takes a look at a controversial shooting four years ago that still has echoes today. Erin Moriarty of "48 Hours" has the story behind the film:
Every day, 16,000 riders run through this Bay Area Rapid Transit, or BART, station in Oakland, Calif.
The sign says "Fruitvale." But there's another name that hangs heavy over the platform: Oscar Grant III.
Wanda Johnson, Grant's mother, showed Moriarty a favorite photo of her "baby boy": "His smile speaks to everybody. His smile speaks to me."
In the early morning hours of New Year's Day 2009, 22-year-old Grant and some friends were on the BART train returning from celebrating in San Francisco. There was a report of a fight, and when the train pulled into the Fruitvale Station, BART police started pulling Oscar and his friends off the train.
Other passengers pulled out their cell phones, and recorded video of what happened next: "In the video I see that there's a officer out with a Taser walking back and forth, cussing, telling people to get off the eff-ing train," Johnson recalled. "And then he grabs one of the boys and takes him off the train. He escorts a couple more off the train and he throws them down on the ground."
One of them is an unarmed Oscar Grant. A BART officer is on top of Grant, trying to handcuff him.
"And as he has his knee in Oscar's neck, Mehserle, he pulls out his gun and he shoots him," Johnson said. "And everybody [goes], 'Why would you shoot him?' "
Transit officer Johannes Mehserle shot Grant point-blank in the back.
Oscar Grant died in the hospital seven hours later.
Actor Michael B. Jordan saw the cell phone video online.
"I just remember being at home on the computer, watching the video," Jordan said, "and just being, like, in awe -- 'Wow, it happened again.' You know, African American kid, a person of color, being beaten, shot, harassed -- this prejudice, the racism, all of that."
Young Oakland filmmaker Ryan Coogler saw the video, too: "I remember the first time seeing it, just having an empty feeling in my stomach.
"And Oscar, being my age, looking like me, wearing the same type of clothes that I wear, his friends looking like my friends -- it really triggered all kinds of emotions, from sadness, to anger, to a sense of helplessness."
The streets of Oakland erupted. Officer Mehserle claimed that instead of pulling out his Taser, he mistakenly grabbed his gun, and fired the fatal shot. Charged with murder, Mehserle was convicted of involuntary manslaughter, and served less than a year in jail.
Coogler saw a story he wanted to tell in a movie -- not so much about the shooting. He wanted to talk about Oscar Grant himself.
"He had made some mistakes in his life," Coogler said. "But he also had some great love in his life, very great positives in his life as well. To be honest, he was a person, just like you, just like me."
But to make his film -- simply called "Fruitvale Station" -- Coogler had a lot of people to convince . . . starting with Oscar's mother.
Johnson said she was "Very hesitant."
Coogler had never actually made a feature film before. But his student films, at USC and elsewhere, had attracted admirers like actor Forrest Whitaker, who signed on as producer.
Whitaker convinced Oscar's mother to say yes.
Then Coogler picked Michael B. Jordan to play Oscar, after seeing him on TV in "The Wire" and "Friday Night Lights."