THE summer afternoon seems to have started pleasantly enough for Paul Gathercole and his mate Robbie Charles.
But before the night was through, Mr Charles would be lying fatally stabbed outside his Mermaid Beach unit, jurors have heard.
On Monday, Mr Gathercole pleaded not guilty to murdering former Coffs Harbour man Mr Charles, but guilty to manslaughter.
The Crown rejected the guilty plea on the less serious charge, so the murder trial began in Brisbane Supreme Court.
Prosecutor Michael Lehane said the two flatmates and darts buddies had been staying at the same unit for quite some time.
Mr Charles, 32, was the younger of the two.
About noon on Saturday, February 1, 2014, both men went to a local darts club function, along with Mr Charles's girlfriend Vanessa Heath.
"There was a lot of drinking throughout the day" although there was plenty of food available too, Mr Lehane added.
Witnesses described the two mates getting along well that day, the prosecutor said.
Mr Gathercole, Mr Charles and Ms Heath then went to the Nobbys Beach Surf Life Saving Club.
They left the club separately but arrived back at the Mermaid Beach unit around the same time that night, the court heard.
The prosecutor said Mr Gathercole took Mr Charles's american staffordshire for a walk, and on returning, it seemed an argument broke out.
The prosecutor said neighbours heard Mr Gathercole saying: "You kicked him in the head, you mongrel dog".
Then, another voice allegedly asked: "Oh my god, oh my god, what have you done?"
Mr Lehane said a witness saw Mr Gathercole with a "bloodstained knife in his hand" and saying "I've done something really wrong".
The prosecutor showed jurors an image of a knife with a 27cm blade.
He said Mr Charles owned the knife and frequently sharpened it for food preparation.
"It went inside him a total depth of around 20cm and that proved fatal."
Jurors were told Mr Gathercole expressed despair and remorse to police in the hours that followed the stabbing.
He asked about Mr Charles's welfare and said he (Gathercole) wouldn't want to hurt anyone, let alone his best friend, the prosecutor added.
Prosecutor Michael Lehane said the Crown expected to call 19 witnesses, mostly from the Gold Coast but also from Burleigh Heads and Melbourne.
At least three police officers and two medical experts including a forensic pathologist were expected to give evidence.
Justice Peter Davis said the trial was expected to last four or five days.
The trial continues. -NewsRegional
Update your news preferences and get the latest news delivered to your inbox.