Lana Clarkson's former publicist has accused the makers of an upcoming Phil Spector biopic of casting doubt on the music producer's conviction for killing the actress.

Al Pacino plays the hitmaker as he stands trial for shooting Clarkson, while Dame Helen Mirren portrays his defence attorney Linda Kenney Baden in the HBO drama.

Spector was jailed for 19 years-to-life in 2009 after being found guilty of shooting the actress at his home, but Clarkson's former spokesperson Ed Lozzi believes writer David Mamet has angled his screenplay in favour of the fallen mogul.

He tells New York Post gossip column Page Six, "Shame on Hbo for green-lighting it. Shame on David Mamet for writing it. And shame on (producer) Barry Levinson for going for the quick buck.

"Their campaign has always been deceitful, evil and defamatory to our beloved friend (Clarkson)... They are portraying real people and using their real names. You can't have your cake and eat it too."

Lozzi fears viewers will start to believe Spector is innocent of the crime after the Tv film airs in the U.S. on Sunday (24Mar13), adding, "The horror of it is, it's a good movie. Five million people will watch it Sunday night and think there is reasonable doubt that Spector is guilty. The movie implies he wasn't even in the room when he shot her in the head."

A representative for U.S. network Hbo has defended Mamet's script, saying, "Mamet approaches the story of Phil Spector as a mythological one, not as a news story, and the film is not an attempt to comment upon the trial or its outcome."