Sue Neill-Fraser was jailed for her husband's boat murder. New evidence could free her.

New evidence in one of Australia’s most controversial court decisions may see Sue Neill-Fraser acquitted of the murder of her husband, renowned medical researcher Bob Chappell.

Circumstantial evidence saw the Tasmanian grandmother sentenced to 23 years in prison for bashing her husband to death on the couple’s yacht in Sandy Bay, Hobart, on Australia Day, 2009.

Despite two failed appeals to overturn Neill-Fraser's murder conviction, Channel 7's Sunday Night reported an unidentified witness will present unheard testimony that may acquit the 62-year-old, who has already served eight years behind bars.

In an investigation by Matt Doran, it was revealed the witness will provide a statement at Neill-Fraser's upcoming appeal hearing detailing private conversations she had with Meaghan Vass, a 15-year-old homeless woman whose DNA was found as a small, dark stain on the deck of the yacht where Chappell was murdered.

During the trial, Vass maintained she had never been on a yacht before and prosecutors successfully argued her DNA could have been accidentally carried onto the yacht on the shoes of police.

Vass has now been called to testify during the appeal hearing, Sunday Night reports.

"There is no doubt in my mind that mum is innocent. She did not commit this crime," said Neill-Fraser’s daughter, Sarah Bowles.

"I’m very confident that we are going to win this and mum should be acquitted at the end of it. We have very strong and compelling evidence that is going to be presented and I think as this plays out, we’re going to witness once of Australia’s biggest miscarriages of justice cases since the Lindy Chamberlain saga."

In a phone call aired by the Channel Seven current affairs program between Bowles and her mother, Neill-Fraser spoke of how she copes with her prison sentence for a crime she maintains she did not commit.

"I think the memories that we collected together over the years are what sustains me now, because whatever they do to me they can’t take those away,” the former horse riding school director said in conversation with her daughter.

"My life as I knew it has come to an end and I just have to try and put the pieces back together."