The man accused of fatally stabbing Sydney real estate agent Vissa Esan allegedly told police after the murder that he "could have done worse".
Adam Brewer, 33, has pleaded not guilty to murdering the 47-year-old at the Pendle Hills real estate agency where he worked on March 13 last year.
Brewer's lawyer, Peter Skinner, told the NSW Supreme Court on Tuesday that self-defence would form the primary basis for their case.
Psychiatric evidence about Brewer's perception of the events leading up to Mr Esan's death and a defence of provocation might also come into play, he said.
Crown prosecutor Michael Barr told the court in his opening remarks on Tuesday that Brewer had intended to cause grievous bodily harm to Mr Esan, who died from a stab wound to the heart.
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Mr Barr said CCTV footage showed Brewer approached Mr Esan inside the business at about 8am and moments later the pair could be seen arguing and struggling.
Brewer then left the arcade but returned "shaking up" and ready for a further fight, the court heard.
Mr Esan then attempted to defend himself with a broom but dropped it and as he bent down to pick it up was hit by Brewer.
He suffered a fatal stab wound to the heart as well as wounds to his left armpit, elbow and fingers.
Mr Barr says any claim of self-defence ended when Brewer re-entered the arcade.
Brewer then fled by a back laneway, stopped at a nearby business where he told a witness he had been "jumped by three blacks at the train station".
Mr Barr said after Brewer's arrest he told a police officers he "could have done worse" and that he "wanted to cut his head off".
The trial before Justice Geoffrey Bellew is continuing.
