DNA centre of Bayliss murder appeal

Jade Bayliss. Photo / Supplied

A lawyer for the man convicted of killing Christchurch girl Jade Bayliss claims there was too much reliance on DNA in his trial.

Jeremy McLaughlin was jailed for life with a minimum non-parole period of 23 years for the murder in 2013.

He was appealing his conviction in the Wellington Court of Appeal today.

A jury found he strangled 13-year-old Jade during a home invasion.

McLaughlin admitted twice going into the Barrington home and stealing items, and using petrol to burn it down on the same day the girl's body was found.

It was later revealed he'd spent time in an Australian prison for the 1995 manslaughter of a 14-year-old.

His lawyer, Robert Lithgow QC, said too much weight was given to evidence of McLaughlin's DNA that was found under the victim's fingernail.

Mr Lithgow claims the DNA was microscopic, and the judge should have told the jury it couldn't be the defining factor in identifying the killer.

"If the DNA was the critical factor in their determination, then it didn't assist them in that"

Robert Lithgow also said the jury was wrongly inclined to find McLaughlin guilty because he lied about committing other crimes.

He initially denied any knowledge of the robberies and fire, before pleading guilty at trial.

Mr Lithgow says those crimes should have been better separated from the murder.

"It can be a distraction from the central proposition that the Crown have to prove that he did it".

Mr Lithgow told the court a separate appeal against the prison sentence is no longer going ahead.