Queensland schoolgirl Jayde Kendall's killer could have his conviction set aside and go to retrial if he wins his appeal.
Brenden Bennetts' legal team on Tuesday attempted to overturn a jury decision last year that found him guilty of murdering the 16-year-old in 2015.
Its argument centred on the assertion the presiding Supreme Court judge erred when she allowed Bennetts' initial statements and conversations with police to be used during his trial.
Michael Copley QC said the information had been illegally obtained because officers already considered him a suspect even though he had not been warned as such.
But crown prosecutor Vicki Loury QC said there was no evidence to suggest police considered Bennetts a suspect when he first spoke to officers and provided statements.
Ms Loury said at the time Jayde's body had not been found and she was simply a missing person.
"The purpose of the questioning was designed to determine where she (Jayde) was, which is what the trial judge found," she said.
Mr Copley said Bennetts' conviction could be set aside and a retrial ordered if the Queensland Court of Appeal rules in his favour.
But Ms Loury said even if the trial judge had erred and the initial statements and conversations with police were excluded, there was enough evidence to uphold Bennetts' conviction.
The Queensland Court of Appeal reserved its decision to a later date.