Lawyers for David Eastman told a jury Thursday there are gaps in the Crown case that cannot be filled.
Prosecutor Murugan Thangaraj SC told the jury Mr Eastman "was deadly serious".
The mafia had no reason to kill police chief Colin Winchester and his death served the organisation no purpose,prosecutors told a jury Monday.
Prosecutors say Mr Eastman later admitted going to the Deakin house while talking to himself in his flat.
He took steps,he took precautions,the prosecutor said,including by wearing his hair differently when he went to buy the murder weapon.
The prosecution is outlining the 10 key topics it says show David Eastman killed Colin Winchester.
David Eastman's defence have pointed to a theory that someone within the Italian mafia orchestrated the hit on the senior police officer.
A police informant told cannabis growers who believed they were being protected by authorities that the crop was Colin Winchester's project,the David Eastman trial heard Tuesday.
A former police informant says he never mentioned the name Colin Winchester to cannabis growers who believed they were acting under some kind of protection,the David Eastman trial heard Monday.
The Crown on Tuesday closed its case in the murder trial of David Harold Eastman.
David Harold Eastman threw rocks at officers conducting covert police surveillance during the investigation into the murder of Colin Winchester.