Father-of-two Mark Rodney Jones has been sentenced to 22 years' jail for murdering Bradley Breward at a Newnham unit on New Year's Day in 2017.
A jury unanimously found the 43-year-old West Launceston man guilty of murder after an eight-day Launceston Supreme Court trial in June.
Jones' Nissan Patrol was stolen from Westbury Road where it had been parked to promote its sale.
The vehicle was uninsured and money from the sale was to be used to pay for a back operation for Jones' long-term partner Rebecca Bailey.
Jones became obsessed with finding the car, with the self-employed builder stopping work so he could spend hours looking for the vehicle.
Physical flyers and social media posts offering a $5000 reward for the return of the Patrol were distributed, with a number of people saying Mr Breward was responsible for the theft.
Jones put a $1000 bounty on Mr Breward's head, which led to a woman named Tina Robertson giving up the victim's location.
Ms Robertson was in a relationship with Mr Breward's friend Cody Lee at the time.
The two men had spent New Year's Eve together and Mr Breward, who was of no fixed address, spent the night of Mr Lee's couch.
Ms Robertson came over early on New Year's Day, but was only in the Newnham unit for a short time because she had a fight with Mr Lee.
As she was leaving Mr Breward insinuated she'd had sex with another man and the comment offended Ms Robertson, so she left the unit and called Jones.
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Jones and his employee Ricky Izard were masked and wearing gloves when they broke-in to the unit via the back door.
Jones interrogated and tortured Mr Breward in a bid to find out where his car was, but the victim didn't give him any information and this made Jones angry.
Jones told police Mr Breward was defiant to the end.
After being punched, kicked, waterboarded and a plastic bag held around his head, Mr Breward told Jones he was dying.
But Jones said he thought the victim was being stupid, so he again wrapped a plastic bag around Mr Breward's head.
The bag was removed after Jones counted to 40, but Mr Breward was blue and wasn't breathing.
Jones, Izard and Mr Lee attempted to give Mr Breward CPR, but no one called an ambulance.
Mr Breward's body was wrapped in a beanbag and tarpaulin and put in Jones' car.
Jones and Izard went to Woolworths, despite Mr Breward's body being in the car, to buy Mr Lee cleaning products and food because Jones thought it was the "right thing to do".
After driving around for hours looking for a mineshaft at Lilydale, the killer and his accomplice decided to buy a raft from Launceston Kmart and dump Mr Breward's body in Lake Eugenana, also known as Melrose Quarry.
Jones lied to police in his initial interview, saying he'd never met Mr Breward and stopped looking for him before Christmas in 2016.
The killer's sentence was backed to February 2, 2017. He will be eligible for parole after serving 13 years.