Crown prosecutor Peter Barnett SC described Scott O'Heir's version of events relating to the robbery of Hilliary Allen as a "load of rot".
Mr Barnett, whose closing address in the Newcastle Supreme Court will continue this afternoon, told the jury to "sit back and think about it for the load of rot it is," when referring to Mr O'Heir's evidence.
Mr O'Heir has pleaded not guilty to the robbery and murder of Mrs Allen in her Singleton home on March 1, 2009.
He previously told the jury that his girlfriend Cheyenne Anderson had a "commotion" with Mrs Allen and that Mr O'Heir tried to help Mrs Allen before he left.
Mrs Allen was found dead in the garage of her home the next morning.
Mrs Allen, 82, died from blood loss as a result of a wound to her right leg.
Mr Barnett said that he did not have to prove exactly how the wound was occasioned, but he said there was enough evidence to prove that the wound was occasioned with some force and not by accident.
Defence barrister Nicolas Moir is expected to begin his closing address to the jury this afternoon.