Rihanna, Kim Kardashian back campaign to free US teen murderer Cyntoia Brown

WASHINGTON - Celebrities have lent their support to a viral social media campaign calling for the release of a Tennessee woman, convicted in 2006 of shooting dead a 43-year-old man who picked her up for sex when she was 16.

Cyntoia Brown, now 29, is serving a life sentence in Tennessee Women's Prison over the murder of Johnny Allen in August 2004, US media reports. In a 2011 documentary aired on PBS' Independent Lens, court footage shows

Brown, who was tried as an adult, explaining she was living in a Nashville motel room at the time with a pimp who abused her and plied her with drugs.

Brown said Allen picked her up and insisted on taking her home, telling her he was an ex-Army sharpshooter and showing off his firearms. She reported his behaviour made her nervous, and that he "grabbed" her forcefully between her legs. "He just gave me this look. It was, like, a very fierce look," she explained.

"But then, he rolls over, like he's reaching to the side of the bed or something. So I'm thinking, 'he's not going to hit me, he's going to get a gun'." "I just grabbed the gun and I shot him," she said. The case has recently returned to the spotlight via a viral social media post - with many arguing

Brown was a victim defending herself. "Something is horribly wrong when the system enables these rapists and the victim is thrown away for life!" singer Rihanna wrote on Instagram, where she has 58.2 million followers.

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"It's heart breaking to see a young girl sex trafficked then when she has the courage to fight back is jailed for life! We have to do better & do what's right. I've called my attorneys yesterday to see what can be done to fix this," reality star Kim Kardashian wrote on Twitter.

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According to reports published on Nov 26, Kardashian has hired a top Hollywood lawyer to help in the campaign.

Other high-profile names including actress Cara Delevingne, actress Ariel Winter and San Francisco 49ers wide receiver Pierre Garcon also expressed their support for the campaign, which has adopted the hashtag #FreeCyntoiaBrown. Meanwhile, an online petition calling for clemency - to be delivered to Tennessee Governor Bill Haslam - has amassed over 325,000 signatures. Attorney Charles Bone, who represents

Brown pro-bono, also intends to petition Governor Haslam for clemency within the next few weeks, according to CBS affiliate WTVF.