Susan Neill-Fraser was convicted of her partner's yacht murder. But is she innocent?

New DNA evidence in the case of convicted killer Susan Neill-Fraser is compelling enough to give her a second shot at freedom, a court has heard.

Neill-Fraser is serving 23 years’ jail for murdering partner Bob Chappell, who went missing from the couple’s yacht moored at Hobart’s Sandy Bay on Australia Day in January 2009.

Mr Chappell’s body has never been found.

Neill-Fraser, 64, is trying to launch a second appeal under new Tasmanian law that require her to first convince a judge there is fresh and compelling evidence.

Her lawyer Tom Percy QC told Hobart Supreme Court on Thursday new DNA evidence satisfied that threshold.

Neill-Fraser’s original trial heard the DNA of then-homeless teenager Meaghan Vass, found aboard the Four Winds yacht, likely got there through secondary transfer.

Forensic expert Max Jones has previously told the appeal the amount of Ms Vass’ DNA meant a direct transfer was more probable, placing her on the boat.

“We say the transfer was almost certainly direct,” Mr Percy said in final submissions.

“This would satisfy the test of fresh and compelling evidence.”

But Director of Public Prosecutions lawyer Daryl Coates QC told the court Mr Jones’ evidence wasn’t fresh as the jury at Neill-Fraser’s trial was told about the possibility of primary and secondary DNA transfer.

Mr Coates added Ms Vass’ DNA could have been deposited on the boat some days after the murder when it was in storage.

Ms Vass’ whereabouts on the night of the murder has been a focus of Neill-Fraser’s lengthy appeal that began in October.

Ms Vass told Neill-Fraser’s original trial she was never on the boat the night of the murder but last year signed a statutory declaration saying she was.

Ms Vass has since told the appeal the statement was a lie and that she signed the document because of threats.

Neill-Fraser was convicted in 2010 of bludgeoning Mr Chappell, winching his body from the boat’s cabin to the deck and dumping it in the River Derwent.

Neill-Fraser’s legal team has also queried the veracity of testing for blood on the yacht’s dinghy and the accuracy of a police winching reconstruction they say was not done in conditions identical to the night of the murder.

Neill-Fraser appealed against her conviction in 2012 but it was rejected.

Her case has been adjourned until next Friday.