The mother of Jean Charles de Menezes is set to come face-to-face with one of the police marksmen who killed her son.
The officer from Scotland Yard's elite CO19 specialist firearms unit will speak about the shooting in public for the first time at the inquest into the Brazilian's death.
Mr de Menezes was shot seven times in the head at point-blank range inside Stockwell Tube station in south London after being mistaken for failed suicide bomber Hussain Osman.
The two police marksman who fired the fatal shots have been granted anonymity and are identified only by the code names C2 and C12.
C12 will give evidence to the inquest, watched by the Brazilian's mother, Maria Otone de Menezes, 63, and brother, Giovani da Silva, 36.
He is expected to be grilled about exactly what orders he was given and why he was so sure 27-year-old Mr de Menezes was Osman.
The inquest at the Oval cricket ground has heard that C2 and C12 were "convinced" the Brazilian was a suicide bomber and about to detonate a bomb on a train.
Coroner Sir Michael Wright told the jury both officers believed an "instant killing" was the only option open to them.
But surveillance officers who followed Mr de Menezes to Stockwell have told the inquest they only said he was a "good possible" for Osman.
These apparent misunderstandings between surveillance teams, firearms officers and commanders at Scotland Yard are expected to be examined.
