BBC News By Sally Chesworth image copyrightMarina Schofield image captionMarina Schofield says lessons need to be learned so "no other mother gets that knock at the door" The mother of a man shot dead by Greater Manchester Police has vowed to fight to release the secret evidence shrouding part of his case. Anthony Grainger, 36, was killed during a covert operation in March 2012. Marina Schofield, from Salford, who lost a legal bid to reveal the sensitive material, said she would continue to try to have it made public. She said lessons needed to be learned so "no other mother gets that knock at the door".