The part of Doreen Lawrence will be played by Marianne Jean-Baptiste, who was nominated for an Oscar for her role as the optometrist Hortense in the Mike Leigh film Secrets and Lies.
The Lawrence family has been consulted on the content of the two-hour film, which is expected to open with the harrowing scene of Stephen's murder by five white youths.
It is also expected to follow the family's personal trauma over the death of their son and to include scenes depicting the judicial inquiry which criticised how the Metropolitan Police handled the case.
The script has been written by Paul Greengrass who will also direct, and it will be produced by Mark Redhead who specialises in factual dramas.
Casting sessions are still taking place for the role of Doreen's husband, Neville, as well for the roles of the police officers involved, including Sir Paul Condon, Commissioner of the Metropolitan Police.
Stephen Hatton Management, the company representing Ms Jean-Baptiste, con- firmed last week that she would be playing the role of Doreen Lawrence, but said the actress was still negotiating the details of her contract.
Ms Jean-Baptiste, who is currently filming The Man for Lenny Henry's production company, Crucial, will be able to draw on her personal experiences of racial discrimination for her role.
In 1996, she was excluded from a group of young actors invited by British Screen to the 50th anniversary of the Cannes Film Festival.
Other well-known names, such as Kate Winslet and Rufus Sewell, were on the list, which did not include any black actors.
Marianne called for a shake-up of the British film industry and said she was disappointed to be excluded - especially as she was the first black British person to be nominated for an Oscar. The same year, Secrets and Lies won the Palme d'Or at Cannes.
Ms Jean-Baptiste, who originally wanted to be a barrister, spent three years at Rada after being brought up on a crime-ridden estate in Peckham, south London. She has also appeared in the film London Kills Me and on the stage in Measure for Measure by the Cheek By Jowl theatre company.
A spokeswoman for Granada Television said casting had not been finalised for the other characters and the programme would deal with the personal as well as political issues of the case.
"The film will show the murder and follow events until the present," she added. "It's not the intention to make a political statement but to investigate on a personal level the destruction Stephen's murder did to the Lawrence family and the effect on them of losing a son. It will also deal with the issue of racism."
Stephen's father, Neville, said he hoped the film would help the family to tell its story on a wider stage and enable the family to get its message across to people who were not aware of all the details.Reuse content