WASHINGTON •In a Foggy Bottom restaurant one recent afternoon, Carl King sat side by side with Nnamdi Asomugha, who plays him in Crown Heights, a new film based on the true story of a wrongful conviction.

Asomugha tried to explain how touched he was by King's real-life story. But King had to admit that initially, he had no idea who Asomugha was.

"Never knew a thing," King said. "How was I supposed to know you played football?"

It was not until filming began on the movie, which recounts King's efforts to free a friend who was wrongly imprisoned, that King heard others on set discussing Asomugha's previous life in the National Football League (NFL).

"I didn't have any reason to Google you," said King, a native of Trinidad who grew up watching soccer, not football. "All I knew was this guy was going to play me and his name was Nnamdi."

"That's hilarious," Asomugha said, slapping King on the shoulder. "I love it."

Asomugha - whose name is pronounced NAHM-dee AH-suhm- wah - is an unlikely star to tell King's improbable story.

Just four years removed from a successful football career, Asomugha has a starring role in Crown Heights.

He portrays King over the two decades he spent fighting on behalf of 18-year-old Colin Warner, who was charged in the fatal shooting of a teenager in Brooklyn in 1980 and convicted despite scant evidence.

Warner maintained his innocence and King sacrificed much of his life, including his marriage and financial stability, to work on his friend's case, ultimately pairing with a tireless underdog lawyer who successfully had the conviction overturned in 2001.

Their story was first told on public radio's This American Life in 2005. Warner Bros optioned the rights to the story, but the project never got off the ground.

In 2010, film producer Matt Ruskin heard the radio segment and approached Warner and King. In need of financing, Ruskin put together a five-minute documentary featuring the two friends and started sending it around.

Asomugha eventually got hold of a copy. "I was blown away," he said, "so I reached out to my manager and said, 'Can we get a script? I want to audition.' "

Landing big parts has not been easy for Asomugha. The 36-year- old's resume is an unusual one in the film world: 11 seasons of professional football with three teams. None of that impresses Hollywood casting directors.

"Any time you're transitioning from one career into another, you can't go in expecting the same level of success that you had in the first one," he explained over lunch. "So there's a humbling you go through."

He says his agent had to fight for auditions. Casting directors assumed he was "emotionally blocked".

Looking back, he concedes, maybe he was. "We're taught from a young age to suppress those emotions, especially playing football.

"First of all, you're not supposed to be crying. And if you're getting too wild, you'll get a penalty. Doing interviews after a game, you can't give your true emotions. You can't tap into them. So when you do that for so long, you go into acting and it can be difficult to suddenly just be open and vulnerable."

When he finally landed the part of King - easily his biggest role to date - Asomugha's approach was not all that different from that of his playing days.

Back then, he took pride in being among the first to arrive at the team facility each morning and the last to leave in the evening. He studied his playbook, pored over film of opposing quarterbacks and wide receivers and studied their mannerisms. He approached his new challenge the same way.

Asomugha had an acting coach named Eden Bernardy fly out to New York and spend time with both him and King. Then together, the coach and former player would dissect the tics and tendencies that made King unique.

"You know in acting you have those moments in a movie where a character yells or breaks down crying and you're like, wow, that's acting?" Asomugha said.

"Selfishly, I'm like, 'I got to figure out that moment' - which is totally the wrong thing to be thinking."

He identified a scene late in the film in which a judge finally exonerates Warner and grants him his release. King was seated behind his best friend in the courtroom, the emotional culmination of a 21-year fight.

"So I asked Carl a month before filming that scene, 'So when you're in court, I know you must've broken down, thrown your hands in the air and there were tears and you were crying and screaming,'" Asomugha recalled.

"He said, 'No, I just smiled.' There was something so real about that. It was much better."

A big part of the role involved mastering King's accent, a melodic and distinctive Trinidadian lilt. Asomugha welcomed the challenge because he felt it would be easier to lose himself in the role.

He worked with a dialect coach, practised each night for months and spoke in the accent on set, even when the cameras stopped rolling.

Crown Heights received a standing ovation when it premiered at Sundance in January and won the festival's Audience Award for US drama.

Asomugha dabbled in acting late in his football career. He signed with a management team - Creative Artists Agency - and in a pitch meeting was surrounded by movie, television and football agents.

In the off-season, he enrolled in acting classes and took on cameo roles in projects such as the TV drama Friday Night Lights.

A Los Angeles native, he also found himself moving in more Hollywood circles when he began dating Kerry Washington, the Scandal actress, in 2012. The two married in June 2013 and now have two young children together.

By that point, his football career was winding down. The bumps and bruises piled up and he played his last football game in September 2013. He had earned more than US$70 million during his playing career and was intent on taking a year off to catch his breath and consider his options.

"I made it nine or 10 days," he said, laughing.

"I was like, 'This is absolutely not what's going to happen' because you're thinking about football the whole time. I immediately started looking up acting coaches. I figured, might as well just dive in now."

Acting gives him purpose. He feels a part of a team again. But compared with football, acting is "more about generosity and giving".

"If we're in a scene together, I want to give you something that allows your performance to be truthful," he said.

"In football, if you're opposite me, I want to destroy you, take your head off. I'm still reading body language, still reacting, still trusting my instincts - same as football - but it's different now."

WASHINGTON POST