A murder suspect said he had killed a seven-year-old girl and her father while he was in prison on another charge, the Old Bailey has heard.
Toni-Ann was shot in the back
Joel Smith asked fellow prisoner Graham Ipswich, a former soldier, if he had shot any children while he was in the Army, the trial heard.
"He said: 'I have done something similar myself'," Ipswich told jurors.
Mr Smith, 32, denies murdering Toni-Ann and Bertram Byfield at a bedsit in Harlesden, north-west London, in 2003.
Ipswich, who is still serving a five-year sentence for wounding, having an offensive weapon and affray, was giving evidence from behind a screen.
He said Mr Smith, who was also in Walton Prison in Liverpool for assault, told him: "We are alike", saying he was like a soldier on the streets.
"I thought I can't be hearing this. It can't be right," Ipswich, who like other witnesses is giving evidence from behind a screen, told the Old Bailey.
"To kill a child, an innocent thing - it's not happening.
"He said he had gone to a house in London. He shot a fellow and a kid.
"I think the man was shot in the chest and I think the kid was shot in the back."
The prosecution said Mr Smith, of no fixed address, had gone to the flat to rob or kill Mr Byfield - himself a cocaine dealer - and shot Toni-Ann to eliminate her as a witness.
They are calling two of Mr Smith's former cellmates as witnesses during the trial.
They said that despite leaving no clues and no witnesses at Mr Byfield's bedsit, he provided the breakthrough in the inquiry himself through "a combination of guilt, a loose tongue and a misplaced trust in others".
The trial continues.