Jimmy and Gail Protos read a statement to the media outside the High Court at Christchurch, after the sentencing of Zariah Jae Samson for the manslaughter of their son, Cory Protos, in 2014.

The parents of a man strangled to death by his girlfriend are "disgusted" that an "unprecedented loophole" saw her murder charge downgraded.

Zariah Jae Samson, 25, was sentenced in the Christchurch High Court on Friday to a six year, three month' jail term for the manslaughter of 30-year-old Cory James Protos.

Samson assaulted Protos for hours, then strangled him with a computer cord before pushing his body under her bed. She confessed the next day.

DAVID WALKER/STUFF Zariah Jae Samson, 25, has been sentenced to six years and three months' jail for the manslaughter of her boyfriend, Cory Protos, in April 2014.

Outside court, Protos' father, Jimmy Protos, said the family was "disgusted" that Samson's murder charge had been reduced to manslaughter.

"We've come out of court today with a life sentence of nightmares, pain and grief while [Samson] gets the murder charge reduced to manslaughter because of a unprecedented loophole in the system."

Justice Cameron Mander included a non-parole period of three years and three months. Samson has already served that term since being arrested for the April 27, 2014, killing, but she will have to face the Parole Board to apply for her release.

SUPPLIED Cory Protos, 30, was killed by his girlfriend of seven weeks, Zariah Samson, then aged 22, at her Christchurch home.

The Protos family will meet Samson next week in an informal restorative justice meeting at Christchurch Women's Prison.

She blew a kiss to her family in court as she was taken out after the sentencing, three days after she pleaded guilty to manslaughter.

Family members told the court of feeling lost and shattered by Protos' "horrific death".

DAVID WALKER/STUFF Protos' parent, Jimmy and Gail, leave High Court at Christchurch after Samson's sentencing on Friday.

His parents, Gail and Jimmy Protos, told of the terrible effects of learning of their son's death through Facebook while they were holidaying overseas.

The family described him as a good sportsman and talented artist. He loved his family and children had been drawn to him.

"He wasn't perfect, but he wasn't a bad person either," Jimmy Protos said.

Gail Protos said she was angry Samson had taken so long to admit her guilt for killing their "beautiful son".

The long court proceedings, including two abandoned trial dates, had been "an endless nightmare", she said.

Jimmy Protos told the court that all the family was left with was their son's ashes, his photo "and a broken life".

But the parents told Samson they hoped she would get the help she needed to turn her life around and reconnect with her children.

The court heard Protos, who was involved with drugs, had been in a seven-week relationship with Samson at the time of his death. Samson told police the violence happened because of "trust issues".

Defence counsel Jonathan Eaton QC said Samson's life had spiralled into drug use and despair after her three children, all aged under five, were taken away by their father to live in the North Island about six weeks before Protos' death.

She had not intended that Protos would die from the strangulation and would have taken "great comfort" from what the family said about their hopes for her to be reunited with her children, Eaton said.

Justice Mander said Samson's decision to tie up Protos was "an intentional and highly dangerous act".

He noted she had been born into a dysfunctional gang family that led to her eventual admission to mental health facilities. She had gone into psychological decline after the loss of her children and had been under the influence of methamphetamine and cannabis at the time of Protos' death.

He hoped the victim impact statements read in court would give her insight into the family's grief and pain and he thanked the Protos family for the dignity and restraint with which they had conducted themselves.

The family's intention to meet Samson at an informal restorative justice conference demonstrated "extraordinary courage", he said.

He read Samson a first-strike warning.