In his closing address to a Supreme Court jury on Friday, Crown prosecutor Daryl Brown said Jesse Willis, 29, had "lied through his teeth" from the beginning.

"His default position in this case is to lie," Mr Brown said. 

The prosecutor said Willis had misled police from the beginning, including an initial conversation he had with a detective in mid-2013 when he said he had no information about the missing Deer Park man's whereabouts. 

Mr Brown said the deception continued on January 19 last year, the day police pulled Mr Ganly's car and body from a flooded mine in Homebush Road, Avoca. 

Mr Brown said Willis' account that Mr Ganly threatened to send bikies to his "front door" after an argument about a gun was also a fabrication. 

"Just lies he had made up in a desperate attempt to explain the gunshot wound to the back of Ricky Ganly's head," Mr Brown told the jury. 

Willis has pleaded not guilty to the murder.

He claims he was acting in self-defence when he shot Mr Ganly at Avoca on or around April 28, 2013. 

Willis' legal counsel, in a closing address to the jury, said Willis had "no other option" than shooting Mr Ganly. 

"Mr Willis believed it was necessary to do what he did... we all have the right to defend ourselves from potential attack,” his barrister said.

The trial continues.