The man accused of murdering Noel Ingham cut his head off and buried his remains in bushland at Dulverton, he told the Burnie Supreme Court on Wednesday.
Giving evidence for the first time in the ongoing murder trial, Darren Ward Gale told the court Mr Ingham died accidentally in the Ulverstone unit the two men shared.
Mr Gale said Mr Ingham died on July 29, 2016 after collapsing into the unit's fish tank, and that he covered up the death because he was worried he would be blamed for it.
He said he lied to police, his neighbours and his own brother about what happened to Mr Ingham for the next three months until his arrest in early December 2016.
Mr Gale told the court he cut Mr Ingham's head off and buried the body.
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He said he drowned Mr Ingham's two dogs and dumped the Jeep Cherokee before burning it.
"Once I had started doing what I had done it was like a big snowball, it got bigger and bigger and worse and worse and I didn't know how to stop it," Mr Gale said.
Mr Gale told the jury his version of events while being questioned by defence lawyer Greg Richardson.
Crown Prosecutor Jackie Hartnett will continue questioning Mr Gale on Wednesday afternoon.