Denzel Washington’s mother Lynne used to talk about how heroin destroyed Harlem, the area of New York where she had been raised and where she raised her family. “Heroin brought the community to its knees,” says Washington. “She would talk about how people who once stood proud ended up lying on their backs. I don’t think the people in the community ever really loved any of the men or women who helped to bring heroin to Harlem.”

What once had been a vibrant area – a heartland for the development of jazz and blues, the home of the Cotton Club and the Apollo Theatre – had by the end of the 1960s slipped into decline. There was a severe shortage of social housing and an escalating crime problem. By the time that her three children were born, Lynne and her husband, also named Denzel, had moved away; Denzel Jr was born in Mount Vermont, on the edge of the Bronx.

Among the people who did help to bring heroin to Harlem was the notorious Frank Lucas. During the early 1970s, Lucas was the most powerful drug dealer in New York, a chinchilla-clad kingpin who amassed a $50-million fortune by selling the purest heroin on the market. He imported his narcotics directly from Vietnam, smuggling them back in the coffins of dead American soldiers. In building his crime empire, he was personally responsible for many deaths.

This shady individual is the subject of Ridley Scott’s latest film, American Gangster, in which Washington stars as Lucas, and Russell Crowe as Richie Roberts, the cop who brought him to justice. In the opening act, Lucas is seen distributing turkeys to the people of Harlem, like a latterday Robin Hood. “There has always been a history for those on the other side of the law, who have made a lot of money from it, to spread the wealth,” adds Washington. “I don’t know whether people loved Lucas for that, but they took the turkeys, and in his mind they loved him for it.”

The 52-year-old actor talks knowledgeably about his subject, unsurprisingly as he talked to Lucas at length about it. Washington has always demonstrated an eagerness to research his roles – for The Pelican Brief he spent months shadowing a newspaper reporter; for Glory he trained with Civil War reenactors; and for Courage Under Firehe attended the National Training Centre at Fort Irwin, California.

Lucas, now 76, served a shortened sentence after testifying against corrupt New York police officers. “And he’s a real raconteur,” says Washington. Like any person, or a star, the further away they get from their heyday, the bigger the number gets.” He stops and laughs. “He’s very persuasive and a very good storyteller. I’d like to tell you some of those stories, but I’m not so good at 9.30 in the morning!”

It is a Saturday morning, on a warm mid-September day in Los Angeles, and Washington is pottering about in his spacious kitchen. Various breakfast sounds, whirring, buzzing and chinking, punctuate our conversation. He is in a cheerful mood. The activity, however, suddenly stops as Washington considers the question – did he like Frank Lucas?

“I’m not sure whether I’ve thought about it,” he muses. “I suppose I couldn’t help but think about the past,” he concedes. “It’s what we [[ researched. But I don’t think he’d do it all again. He has a brilliant young son, about 11, and he lives for that little boy. Frank talked in graphic terms about how what he saw as a child turned him to a life of crime. It started him off stealing chickens and then he moved up the chain.”

This key event, recorded in an interview in New York magazine in 2000, inspired Scott’s film and took place when Lucas was only six years old. One night, the Ku Klux Klan visited the shack in which he lived and dragged his 12-year-old cousin out. They tied his hands, thrust a shotgun into his mouth and pulled the trigger.

“Frank spoke to me about that being a turning point,” Washington says. “The men responsible were figures in authority, and they murdered him for ‘reckless eyeballing’, basically just for looking at a white girl. After that, Frank was the eldest child and felt an obligation to put food on the table.” By the time he was 16, Lucas was on the run, a hardened criminal. His cousin’s grisly fate is referred to in the film, and it is there that audiences can make their judgment about Lucas. For Washington, however, it is not so simple.

“It’s not for me to judge him,” he says. “Basically, Frank’s a human being who’s done some awful things and paid the price for it.” When the New York magazine writer asked Lucas about the morality of killing people, selling millions of dollars’ worth of heroin and playing a significant part in unravelling the social fabric of Harlem, Lucas bristled. “What choice did I have? I wanted to be on Wall Street, but I couldn’t even have got a job as a f***ing janitor.”

He entered a life of petty crime before moving to Harlem and finding work as a driver for one of the neighbourhood crime lords. After his boss’s death, Lucas took control, importing high-quality heroin direct from Vietnam. He was eventually caught by detective Richie Roberts in 1984, who figured out how Lucas was transporting the heroin. The two men struck a deal: Roberts would ensure that his lengthy sentence was reduced, and Lucas would in turn give evidence against the corrupt police officers who made money from gangs. Lucas served a 15-year prison sentence. Washington felt indebted to Lucas for sparing him so much time, and when the production wrapped, chose to make him a gift of a house. “Frank wanted me to get him a Rolls-Royce,” he laughs, “but his eldest son said that he needed a house! So I got together with Brian Grazer [the film’s producer] and that’s what we got him.”

Those who know Washington would not be surprised by his magnanimity of spirit and purse. The New York-born actor is famously considerate and courteous. He is a spokesman for the Boys’ Club of America, an organisation to which he belonged as a child, and is a supporter of the Nelson Mandela Children’s Fund and the Aids hospice the Gathering Place. He notes that of his three best friends in his early teens, one was murdered, one died from an Aids-related disease, while the third is serving a 25-year prison sentence; he is grateful for his mother’s careful guidance.

“I believe in positive thinking and being grateful for what’s about to happen. It’s not what you have, it’s what you do with what you have.” This is an attitude fostered by his mother, who raised her children alone after she and Denzel Sr divorced.

Conscious of the environment in which her children would grow up, Lynne Washington sent her two youngest to boarding school, and Denzel Jr went on to graduate in journalism from Fordham University. There, he developed an interest in acting and was soon snapped up by the New York Shakespeare Festival.

Washington’s first feature role came in the year that he graduated from Fordham, starring in Wilma, a TV movie about the American sprinter Wilma Rudolph. On set he met Pauletta Pearson, an actress, singer and musician. The pair married five years later and now have four children. They renewed their vows in South Africa in 1995, with Desmond Tutu officiating.

“You need to have a strong woman to tell you that you are full of s*** once in a while!” he smiles. “You must centre your life around your family rather than your work.”

It’s a lesson that Frank Lucas has learnt the hard way, although Washington Jr has high hopes for Lucas Jr: “He’s a straight-A student, and you can see through him what Frank Lucas might have become had his life gone in a different direction.”

American Gangster is released nationwide on Nov 16

FROM HIGH-MINDED MEDIC TO CORRUPT COP: HIGHLIGHTS FROM THE DENZEL WASHINGTON RÉSUMÉ

ST ELSEWHERE (1982-88)

Like George Clooney, Washington got his big break in a medical drama, playing Dr Phillip Chandler in this influential, offbeat series set in a dilapidated Boston teaching hospital. Juggling the role with film work, he was a fixture for the show’s entire six-year run. His co-stars included Helen Hunt, Christopher Guest and Ray Liotta.

GLORY (1989)

Blood, bayonets and an Oscar for Best Supporting Actor in Edward Zwick’s civil war epic, as a former slave who distinguishes himself in one of the US Army’s first black regiments. In the same year, he played a modern British soldier – with a convincing cockney accent – in For Queen and Country.

MALCOLM X (1992)

Having portrayed the antiapartheid campaigner Steve Biko in Cry Freedom in 1987, Washington played a more belligerent type of activist in Spike Lee’s fêted biopic. By turns charming and zealous, his performance secured his place at the top table. Unwilling to be typecast, he turned down a later offer to play Martin Luther King.

TRAINING DAY (2001)

Washington relished a rare villainous role, his exquisitely unpleasant turn as a corrupt cop winning him the Best Actor Oscar. He was only the second black man after Sidney Poitier to win the award, on the same night that Halle Berry became the first black woman to be named Best Actess.

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