A man accused of killing Bradley Breward over a stolen car told police he still doesn't know who was actually responsible for the theft, a jury has heard.
Mark Rodney Jones has pleaded not guilty to murdering Mr Breward at a Newnham unit on New Year's Day in 2017.
In a police interview about a month after the alleged murder Mr Jones said he and Ricky Izard went to the unit after being tipped off about Mr Breward's location.
Mr Jones said as he stood at the unit's backdoor he was "pretty nervous", started shaking and nearly left.
"I'm not a confrontational person ... because Ricky was with me I didn't want to look like a goose," he said.
"Thinking about it now I had no idea what I was going to do."
Mr Breward was allegedly half asleep on the couch, so Mr Jones sat next to him while Mr Izard went to check who was in the bedroom.
The court heard a struggle between the alleged victim and Mr Jones started straight away, with the accused killer throwing a number of punches.
"He was really defiant," Mr Jones told police.
"He wouldn't say anything."
The court heard Mr Breward's lack of co-operation with the interrogation about the stolen car angered Mr Jones.
Mr Jones proceeded to waterboard Mr Breward and twice held a plastic bag over his head.
"You get these ideas off TV," Mr Jones said.
But Mr Breward was not breathing when the plastic bag was taken off his head the second time, the court heard.
"It's not like on TV where you see things happen and everyone's OK," Mr Jones said.
The court heard Mr Jones, Mr Izard and the owner of the unit Cody Lee tried to give Mr Breward CPR.
Mr Jones told police he offered to take Mr Breward to the hospital because he didn't want him to die, but Mr Lee said to let his friend die because he didn't deserve to live.
It was alleged the three men wrapped Mr Breward in an empty beanbag and in tarpaulin before putting him in Mr Jones' ute.
"I just couldn't believe what happened," Mr Jones said.
Mr Breward's body was allegedly dumped at Lake Eugenana on the day he was killed, but it wasn't found until February 3.
Forensic pathologist Dr Donald Ritchie gave evidence in the Launceston Supreme Court on Friday.
Dr Ritchie said Mr Breward's body was in a moderately advanced state of decomposition, with soft tissue missing from his neck and chest.
The court heard during Dr Ritchie's examination he found Mr Breward's heart and lungs had liquified, weighing 20 grams and 15 grams respectively.
"They were so decomposed that grossly and under the microscope I was unable to make any findings," Dr Ritchie said.
The trial before Justice Robert Pearce will continue on Monday.