Jamie Simpson was killed in 2008
A teenager has told a court he must have stabbed a Matalan store manager but said he could not recall doing it.
Seven men are at the Old Bailey accused of murdering Jamie Simpson, 33, during a failed robbery at the store in Hackney, east London, in March 2008.
One of the accused, Kobina Essel, 18, of east London, said he was "panicking" as he stabbed Mr Simpson.
Essel, who denies murder, said: "I was panicking and scared. I can't give any explanation but I know I did do it."
Anthony Maina, 20, of Canning Town, east London, Duane Owusu, 20, of Manor Park, east London, Simeon Jumah, 25, of Manor Park, Roy Williams, 31, of Edmonton, north London, and Jamal Chambers, 18, of Poplar, east London, and a 17-year-old youth who cannot be named also each deny murder.
Maina, Essel, Jumah and the 17-year-old have all admitted conspiracy to rob - a charge the others deny.
The court heard Mr Simpson was fatally stabbed during the planned raid on the store over the Easter weekend as he cashed up the day's takings.
Essel told the court he remembered seeing Mr Simpson slumped on the floor and then running away, adding: "I am sorry for what I did."
He said: "I don't remember what was going through my head. I don't remember me doing anything to him but by the way he slumped I know I'd injured Mr Simpson."
The case continues.