The hardest of the gangs, though, are the white supremacists, who rally around ideology rather than racketeering.

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For its part, the FBI says it hasn't seen any links between American white supremacists and groups like al Qaeda.

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An ardent opponent of the death penalty, she has kept some of the nation's most despised criminals -- baby killers, bombers, white supremacists and terrorists -- off death row.

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An American activist, Patrice O'Neill, is here to share her experiences of fighting hate-crime in the US - white supremacists targeting African Americans, Jews, Mexicans, Native Americans and gay people.

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It is almost certainly the case that, for many white supremacists, the music doesn't motivate them to violence so much as reflect attitudes about hate and violence they already possess.

CNN: Hate with a beat: White power music

British authorities adopted a similar strategy in 2009 when the names of 16 people barred from entering the UK for promoting hatred - including Islamic extremists and white supremacists - was published by then-Home Secretary Jacqui Smith.

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While authorities have not said whether they have linked the deaths of Hasse and McLelland, or the involvement of white supremacists, Texas law enforcement agencies did warn shortly after the November 2012 indictment that there was "credible information" that members of the Aryan Brotherhood were planning to retaliate.

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