Marcia Collins, the sister of Sean Riggs told Daybreak that she is happy that the IPCC has apologised to her family.
Last year an inquest into Sean Rigg's death found that officers had used "unsuitable force" when he died in Brixton police station in 2008.
Marcia said: "It's been a long struggle, we shouldn't have had wait five years to get to this stage."
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Flammable cladding has been found on 75 high-rise buildings across 26 local authority areas, MPs have been told.