Bay of Plenty man Brad Callaghan has pleaded guilty to the murder of Auckland mum Carmen Thomas.

Callaghan appeared in the Auckland High Court his morning where he admitted to murdering the 32-year-old woman, with whom he had a relationship and shared a son with.

Carmen's dismembered remains were found in the Waitakere Ranges October last year.

He's also pleaded guilty to a charge of perverting the course of justice after he initial denied any involvement in her death.

Carmen was last seen alive on June 27, 2010 and was reported missing on July 13.

Callaghan was arrested and charged with her murder on September 21 and has been remanded in custody ever since.

The matter of Callaghan's plea was embargoed by the Court until 1pm today so the victim's family could be advised of the plea.

Officer in charge of the homicide investigation, Detective Inspector Mark Benefield says he's proud of leading a team of dedicated staff who worked hard to resolve the case and which has resulted in today's plea.

'This has been an emotional investigation from the outset.

'The families on both sides have been ripped apart by violence and this development is particularly pertinent on White Ribbon Day where we all come together to express our intolerance of family violence.”