Duwayne Brooks was with Stephen Lawrence on the night he was killed in a racist attack in 1993 in Eltham, London.
Brooks is currently a Liberal Democrat councillor for Downham, London.
Doreen Lawrence has said it will "take a while to gain trust" after she met with the Metropolitan Police commissioner over smear claims.
Scotland Yard has been confronted with another accusation of underhand tactics in its investigation of the murder of Stephen Lawrence.
The father of murdered teenager Stephen Lawrence said he felt "betrayed" by allegations the Met Police tried to smear his family.