Detectives "grilled" a woman for three hours about her relationship with the estranged partner of murdered Aucklander Carmen Thomas.

North Shore police are appealing to the public to help identify the body of a woman found floating in the Waitemata Harbour yesterday.

Police are worried about the health of a Ngaruawahia man who's been missing since Wednesday.

Police are believed to have tracked the movements in Waikato of two men who knew Carmen Thomas - at the time that her car was abandoned in Hamilton.

The sister of murdered mum Carmen Thomas has broken her silence as new information emerges about the police inquiry.

Police say the discovery of missing four-year-old Lucas Ward's body was a relief for searchers but "incredibly distressing" for his family.

Police hunting for the killer of Carmen Thomas returned to a stretch of rural road in southeast Auckland yesterday to search for clues.

As police pull out of the search for 4-year-old Lucas Ward, the head of the investigation has admitted the Gisborne boy may never be found, but his family are not giving up.

The grandfather of missing Gisborne toddler Lucas Ward says the family hasn't given up hope and will keep on searching.

As the search for Gisborne pre-schooler Lucas Ward enters its sixth day, police have no plans to scale down their search.