Richard Henriques QC, for the prosecution, told Preston Crown Court in his closing speech: 'If ever a crime was committed jointly and together, then this was that crime.' He said the boys both took James, two, from a shopping precinct in Bootle, Merseyside, and stayed together for more than 10 hours during that day.
He asked the jury whether one of the defendants could have delivered at least 30 blows to James with no criminal participation from the other. The prosecution has claimed that the two boys - who were aged 10 at the time - abducted James and stoned and beat him to death.
Both deny the charges, and deny a further charge of attempting to abduct a second two- year-old on the same day, 12 February this year.
The trial resumes on Monday.