THE ex-boyfriend of a former Bolton woman who went missing in New Zealand 10 years ago has admitted killing her.

But the location of Sara Niethe’s body still remains a mystery—causing more heartbreak for her family.

Mark Pakenham pleaded guilty to manslaughter when he appeared before the High Court at Hamilton.

He admitted administering the class B drug methamphetamine, also known as crystal meth.

Pakenham denied knowing what happened to Miss Niethe, despite being the last person to see her alive on March 30, 2003.

Shortly after her disappearance he told the media that he prayed for her safe return.

But in 2011 he was arrested and accused of murdering the mother-of-three.

The charge was reduced to manslaughter ahead of Pakenham's trial which was due to start in May.

Miss Niethe, aged 30, went missing after leaving Pakenham's house in Kaihere, 35km northwest of Morrinsville, Waikato. She was heading back home to Kerepehi, about 10 minutes drive away.

Police initially thought she might have had an accident so combed canals and riverbanks in the Hauraki Plains.

As the days went by and her daughter Danielle reached her 10th birthday, police discounted suggestions Ms Niethe had left home as she had planned her daughter’s party.

Miss Niethe moved to New Zealand in 1975 with her family, including brother Lee and her dad David Marbeck. They spent 11 years living in Auckland. Mr Marbeck moved back to Bolton in 1986 and lives in Tonge Fold.

He has flown to New Zealand twice since his daughter’s disappearance, but told The Bolton News previously he would not return to watch the court proceedings and would only go back if her body was found.

Det Sgt Glen Tinsley said police were hopeful Pakenham would “show some compassion for the family and let us recover Sara's remains”.

Det Sgt Tinsley said there were mixed emotions about Pakenham's guilty pleas, which included two charges of injuring with intent to injure two other women in Auckland between 1990 and 1992.

He added: “It’s bittersweet but our determination is all around getting Sara back.”

Pakenham was remanded in custody and will reappear in the High Court on June 28 for sentencing