Justice 30 years later for Terri Friesen, whose baby was killed in 1989

Terri Friesen told the Herald outside the courtroom that she was "just overwhelmed, relieved and thankful". Photo / Supplied

A woman has had a conviction thrown out almost 30 years after she falsely admitted to killing her baby daughter.

In 1989 Terri Louise Friesen, then 21, was found guilty of the manslaughter of her 7-week-old baby, Chantelle, at the conclusion of a jury trial.

The Court of Appeal today quashed Friesen's conviction.

Outside the courtroom, Friesen told the Herald she was "just overwhelmed, relieved and thankful".

Law student Kelly Phillips told media she first became aware of Friesen's case after watching a TVNZ programme called I Am Innocent.

She called Friesen to discuss the case and managed to get private investigator Tim McKinnel on board to get the conviction quashed.

Phillips said she was "shaking" throughout the brief court hearing today.

"I can only imagine what it's been like for Terri to sit through 30 years of wrongful conviction," she said.

"Hopefully this is the last time that this painful, horrible memory will be thrown up in her face in the pursuit of justice."

McKinnel was also present in court and spoke to media outside.

"She's as innocent as you and I to any offences," he said.

"Without Kelly, she would still be convicted of killing her own child."

Terri Friesen, left, leaves the court of appeal in Wellington after having her conviction quashed. Photo / NZME

Phillips said if the criminal justice system was working the way it was supposed to, Friesen's name would have been cleared long ago.

Friesen falsely confessed to the crime to protect her then-partner, Brownie Walter Broughton. She was sentenced to six months' supervision.

Thirteen years after taking the fall for a crime she didn't commit, Friesen was proven innocent when Broughton walked into a Christchurch police station, admitted it was him and begged to be charged with manslaughter.

He confessed to shaking his infant daughter to death and letting his de facto partner take the blame.

Broughton said he had found God and wanted to atone for his sins.

He had earlier approached police in New Plymouth and tried to confess, but no action was taken.

Broughton was eventually convicted in relation to Chantelle's death - but Friesen's conviction was never expunged.

After Broughton confessed, Friesen told a court that she falsely admitted shaking the baby because she did not think the baby's father could handle spending time in jail.

She claimed the police also threatened that if one of them did not own up, her other daughter would be taken into Social Welfare care.

Chantelle died from non-accidental injuries as a result of being shaken.

A post-mortem examination revealed she had suffered from a brain injury and cracked ribs - an injury her mother says she knew nothing about.

In a 2001 interview with the Herald Friesen said she was seeking a pardon.

"I just want my name cleared," she said.

"I'm relieved that the truth is out there. I'm quite numb, it's pretty freaky."

The mother of seven described Broughton as a violent and evil man.

She claimed that at the time of Chantelle's death, police told her Broughton would die if he was sent to prison.

"He really looked like the broken one," she said.

"I was in a state of shock ... They looked at me as the hard one."