Rubin "Hurricane" Carter, the US boxer whose wrongful conviction for murder was the subject of a Bob Dylan song and a film starring Denzel Washington, has died aged 76.
Carter spent 19 years in prison and was released in 1985 after it was determined he did not get a fair trial, with his case having become a symbol of racial injustice.
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The singer had been tweeting in support of migrants when she was bombarded with abusive messages.
Ministers are reportedly considering plans in a bid to lower inward migration.
In a tweet on Saturday, the US president didn't give a reason for his absence but said he wished"everyone well and have a great evening".