Thomas Appleby's "selfish plan" to get drugs from a man - by force if necessary - ended with a stabbing death that was captured on a home security system.
A jury last year found the 25 year old not guilty of Robert Frescon's murder, but could not reach a majority verdict on a manslaughter charge.
Appleby pleaded guilty to that offence in a Brisbane court on Thursday - three days after Mr Frescon would have turned 37.
Appleby, who had bought drugs from Mr Frescon previously, set off from the Gold Coast with Damian Marko Markovski and a plan to get methylamphetamine on credit or, if that failed, using violence, crown prosecutor Steven Dickson said.
A security camera in Mr Frescon's lounge room in his Kelvin Grove, Brisbane, home captured Appleby being let in at 1.37am on January 18, 2019.
Footage played in court shows the men talking, becoming aggressive and Appleby picking up two kitchen knives from a shelf.
He threatened Mr Frescon, who fought back, knocking Appleby to the couch. Then the mask-wearing Markovski came in and stabbed Mr Frescon in the neck with a knife.
Hours later Tania Wilson found her brother dead after he failed to arrive at work.
Appleby was on the run for two days during which he punched a shop owner while stealing cigarettes, but when arrested admitted his involvement and offered to testify against Markovski.
Ms Wilson sobbed while directing angry comments at Appleby, saying she often relived the moment when she found her brother's body.
"The last visual memory of Robert is the one you gave me ... I found him where you left him, in his home, behind the couch, laying in a pool of his own blood," she told the court.
Ms Wilson said Appleby left the house without trying to save Mr Frescon or calling for an ambulance.
"You left knowing what you had done and you ran like cowards and went into hiding until you were caught."
She told Appleby he would have to live with the impact of his actions on her family and his.
"The irreparable damage you have caused will forever haunt you," she added.
"Your actions, no matter how many times you say you're sorry, will always cause heartache and pain to your family."
Defence barrister Angus Edwards said Appleby went to the house unarmed and knowing there was CCTV.
"He used the knives to threaten the deceased but did not attempt to stab the deceased despite the fact that he had plenty of opportunity to do so," Mr Edwards told the court.
Appleby was "a terrible addict" who was unaware Markovski was armed and did not intend for Mr Frescon to die or be seriously injured.
Mr Edwards said the footage shows Appleby's "look of shock and horror" when he realised Mr Frescon was bleeding.
Appleby has been beaten and had boiling water thrown at him in custody for offering to give evidence against his co-accused.
Brisbane Supreme Court Justice Lincoln Crowley said Appleby was "very much to blame for the unlawful killing" even though he had not stabbed Mr Frescon.
The result of carrying out Appleby's "selfish plan" was the senseless death of Mr Frescon in his home.
"It was a disgusting act perpetrated in the course of carrying out a despicable plan to use whatever force of violence might be necessary to get drugs from Mr Frescon, willingly or otherwise," he added.
Justice Crowley sentenced Appleby to nine years behind bars for manslaughter, ordering he be eligible for immediate parole, having spent nearly three-and-a-half years in custody.
