It is inconceivable an Irish father-of-two accidentally impaled himself on a screwdriver during a fatal fight with a fisherman next to Perth's Swan River that was sparked by a "racist" comment, a jury has heard.
Andrew Doan, 35, is on trial in the Supreme Court of WA, accused of murdering Charles John McCarthy, 32, in the early hours of December 23, 2017.
Doan and Tien Vu Huynh had been fishing without much luck for about two hours when Mr McCarthy walked by with his wife Nicole and friend Jason Mikel Curran, who made the contentious remark about the Asian men getting into trouble with Fisheries for their catch.
It was a "smart-arse, throwaway" comment, prosecutor James Mactaggart told the jury in his closing address on Thursday.
However, Doan said the remark was hurtful and racist because there was a stereotype "that all Asians catch undersize fish".
Mr Mactaggart said he should have just ignored it.
Instead, he followed the trio down the road and angrily confronted them, brandishing a screwdriver and shouting "I'm going to stab you".
According to Doan, Mr McCarthy then flew into a "demonic rage" so he retreated to his car.
The prosecution says, however, that Mr Curran went back to the fishermen's utes to take photographs of their number plates so he could report Doan's threats to police and was struck by the accused, who yelled at him to delete the images.
Mr McCarthy went to intervene, despite his wife's pleas to stop, and the next thing she saw was "his lifeless body drop to the ground".
Doan claims the deceased had raised a fist to punch him, so he closed his eyes, threw up his arms up to protect his face "bracing for impact" and forgot the screwdriver was in his hand.
"It is inconceivable, impossible that Mr McCarthy could have tripped, fallen, stumbled - or in some way not really made clear - impaled himself on that screwdriver," Mr Mactaggart said.
"Nothing of the sort occurred."
The prosecutor said it was also inconceivable Doan forgot he was holding the screwdriver.
"He never let that screwdriver out of his grasp," Mr Mactaggart said.
"Mr Doan deliberately stabbed Mr McCarthy. This was a conscious and voluntary act."
The jury is expected to deliberate its verdict on Friday.