Closing his speech, Mr Sherrard said: "The 17-year-old took matters into his own hands that night.
"Like the victim on 6 September, he stabbed Jodie without care.
"As Svenson told you in his evidence - he said 'if I went on my own this would not have happened'.
"He said 'I take responsibility for everything else - for asking Manuel for a lift, for burning my clothes, but I am not responsible for the murder of Jodie Chesney'."
The trial will resume at 10:00 on Monday.