Tasmania murder a 'cold-blooded execution'

After shooting and dismembering his friend in an execution-style killing, Jack Harrison Vincent Sadler went around northern Tasmania dumping his body parts into wheelie bins.

Sadler was on Friday sentenced to 32 years' jail for murdering Jake Anderson-Brettner, an act which Justice Robert Peace described as calculated and cold-blooded.

The killer lined a small room in his Launceston home with plastic before inviting Mr Anderson-Brettner over on the night on August 15, 2018.

There he shot him at least three times with a pistol, once while he was on the ground.

Justice Pearce said he could not determine exactly what motivated the crime, but noted Sadler was "angry" with his friend, likely over illegal drugs.

Sadler's then-girlfriend Gemma Clark was in the nearby bedroom and heard Mr Anderson-Brettner say "please man, don't".

She had earlier purchased bleach, firelighters, gloves, overalls, safety glasses, a saw, cling wrap, vinegar and reusable bags at Sadler's request.

She also bought cayenne pepper and chilli powder, which were used to mask the smell of Mr Anderson-Brettner's remains.

After Sadler cut up the body, the pair searched online for which suburban bin collections were due in the morning.

They drove around Launceston and dumped remains-filled bags into bins. They've never been found despite extensive searches.

Mr Anderson-Brettner's torso was thrown off the side of a highway into bushland about 40 kilometres outside Launceston.

It was discovered several days later, sparking the police investigation.

Sadler appeared from prison via video link in court and was motionless when the sentence was handed down.

"It was an intentional cold-blooded killing, committed after pre-planning and preparation," Justice Pearce said.

Sadler had an "absence of remorse", tried to cover his tracks and lied to police during interviews, the judge added.

Sadler had pleaded not guilty, but the jury rejected his version of events that Mr Anderson-Brettner was shot by anonymous drug dealers from Victoria.

Justice Peace said the traumatic effect of the murder would impact Mr Anderson-Brettner's family for the rest of their lives.

"Nothing would ever bring Jake back," his mother Claudette Brettner said outside court.

She said she hoped Jack could turn his life around after going down the wrong road.

"I hope to God that he does. That's all I can hope for. While he's breathing, there's still hope that he can change."

Sadler's sentence was backdated to August 2018 with a non-parole period of 20 years.

Clark is serving five-and-a-half-years' jail after earlier pleading guilty to being an accessory after the fact and failing to report the killing.

In the aftermath of the shooting, the pair destroyed evidence, cleaned the house with bleach and burned curtains and carpet from the room.

The pistol was vacuum packed and concealed in the garden, while ammunition and the silencer were taped into PVC pipes and hidden.

Mr Anderson-Brettner's partner went to the house the morning following the murder after he didn't come home.

Sadler told her he had been out looking for him.