Police hunting for missing Christchurch teenager Hayden Miles today said they are pursuing "multiple lines of inquiry".
Although police are still publicly calling the 16-year-old's disappearance a missing person's case, it is understood that a parallel homicide investigation has been underway for days.
The shift in police focus coincides with an ongoing detailed forensic search of a run-down house at 612 Cashel St, Linwood.
The search widened to all houses within 200 metres of the address yesterday.
Operation Hayden head, Detective Senior Sergeant Tony Hill, said the police Search and Rescue team will today complete their search of the area around the Cashel Street property.
He said that "no items of interest have been located".
The detective added that the focus during the weekend will be the ongoing forensic examination at the Cashel St address, which is expected to continue through the weekend and until such time as all examination work is completed.
Investigators will also continue to speak to people who are offering information as to the events leading up to Hayden's disappearance.
Since the teen's disappearance the investigation has spoken to or had involvement with about 500 people, across "multiple lines of enquiry", police say.
More than 30 police staff are working fulltime on the investigation, with additional specialists being brought in as required.
Police have a dedicated member liaising with Hayden's family, who are being kept fully informed about the progress of the investigation but have refused to speak to the media.
Hayden has been missing since August 22.
There had been "mixed reports" according to police that the youngster had been mugged shortly before his disappearance.
Hayden last spoke to his mother Jacqui from an unknown person's cellphone in the Linwood area before going to a friend's house on Cashel St on August 22.
That was the last time anyone has seen or heard of him.
But the Cashel St property - which neighbours say is a well-known local 'tinny house' (where cannabis foils are sold) - has been a hive of police activity over the last week.
The dilapidated property remains cordoned off with police tape while private security guards patrol its perimeter.
Specialist police have been paying particular attention to an area at the rear of the property which they have now covered with a large tent.
All of the building's windows have been blacked-out in recent days for a luminol examination - the technique used by forensic investigators to detect trace amounts of blood left at crime scenes.
The luminol substance is sprayed evenly across an area and blood flecks are illuminated in a darkened room.
Police have again refused to comment on revelations that blood has been found inside the property.
A spokesman said: "There will be no comment while forensic examinations are carried out."
The police were also tight-lipped over the move to a homicide inquiry, with a spokesman saying: "We won't be making any further comment."
- APNZBy Kurt Bayer @KurtBayerAPNZ Email Kurt