It seemed like a crazy reach to fledgling writer-director Ryan Coogler.
His agent suggested offering the role of Wanda, Oscar Grant's mother in "Fruitvale Station," to Octavia Spencer. She had just capped a remarkable awards season with the Academy Award for her turn as Minny Jackson in "The Help."
"She was somebody I didn't think we could get. It helped having Forest [Whitaker as producer]. But our movie was so small, it's not a big movie at all. My agent said it might be a good thing to get Octavia for the mom," Mr. Coogler recalled.
To which the filmmaker replied: "Oh, man, you're crazy." However, he took his agent's advice to keep an open mind and also enjoyed the support provided by Mr. Whitaker, another Oscar winner. Ms. Spencer signed on, after initially saying no.
She looked at the actual video of the shooting of unarmed, restrained Oscar Grant on an Oakland, Calif., train station platform on Jan. 1, 2009, and felt only anger and passed because "I had nothing to offer it," she told "CBS This Morning."
Her agent made her read the script, and she was surprised and impressed by Mr. Coogler's storytelling skills and agreed to take the role. The mom is a key part of the film, whether she's visiting her son behind bars, chiding him not to talk on the phone while driving or keeping a prayerful vigil near his hospital room.
Mr. Coogler, 27, had hoped to land Michael B. Jordan from the get-go as Oscar Grant.
"He's done so much work. He's worked in a lot of television, and while we were working on the film, two of his more recent movies got released, one called 'Chronicle' and one called 'Red Tails,' " Mr. Coogler said by phone during a Philadelphia publicity stop.
"He's played a lot of supporting characters and whenever his character would leave the screen, you'd always miss him. You'd wish he was still on camera, when he was working on stuff like 'The Wire' and 'Friday Night Lights.'
"I needed somebody who looked like Oscar, I needed somebody who could carry a whole film, and he was probably around that age and understood what it felt like to be 22 and be dealing with all those things. He was the perfect person for the role."
Mr. Jordan also seems at home playing the devoted dad to a 4-year-old, portrayed by Ariana Neal, who was cast out of Atlanta.
"They're both really talented. They would hang out together on the set," and play games, including cards.
Mr. Coogler starts the movie with the real footage of Grant being shot on the platform at the Fruitvale Station stop of the Bay Area Rapid Transit or BART.
"Initially, I didn't want to open it that way, I just wanted to let the film play out as it goes, but my editors -- Michael Shawver and Claudia Costello -- are not from the Bay Area. Mike's from Rhode Island and Claudia's from Rio, and they had offered the idea of starting with some element of what happens on the train."
It was an issue of perspective, Mr. Coogler realized, since he is from the Bay Area. They reminded him not everyone knew the story, and he agreed. "It felt right once we put it in there."
Then known as simply "Fruitvale," the dramatic film won grand jury and audience awards at the Sundance Film Festival in January. Today, it's generating early Oscar buzz.
Mr. Coogler, who earned an MFA in film and television production from the University of Southern California, was home on Christmas break when Oscar was shot Jan. 1, 2009, and protests later erupted.
Angry demonstrators smashed storefronts, set fire to cars and clashed with officers after a BART officer forced the unarmed man face down on the platform and shot him. "I saw that stuff up close and personal," he recalled.
"As an artist, any time things impact you deeply, your mind kind of goes to getting it out through your art. Musicians do that. Photographers do that. Painters do that. Even cooks do that. ... When I saw the fallout that happened afterward, I think my mind went there even more."
When Mr. Coogler met Oscar's family, they listened more than they talked.
"Meeting his mom in person was really moving because I realized how young she was, how young she is, to have gone through what she's gone through."
Asked if Oscar's relatives imposed any ground rules, he said, "They were really trusting. ... I told them I wanted to tell the story from a balanced perspective, I was interested in showing him as a man, as a human being and that meant some things they might be uncomfortable with."
The officer who shot Grant said he meant to draw his Taser, not his sidearm. He was convicted of involuntary manslaughter in January 2010 by a Los Angeles jury that rejected a second-degree murder charge.
As for what Mr. Coogler thinks happened on that platform as New Year's revelers were heading home, he cuts to the heart of the matter and says simply, "Somebody's life was lost unnecessarily."