A woman and her son found dead in a Christchurch house can now be named as police confirm they have ramped up the investigation to a homicide inquiry.

The pair were Beverley Joan McIlraith and her son Nick Myles McIlratih

Beverley was in her 80s and her son, who lived with her, in his 40s.

Police are still working to formally identify the pair, who may have been dead in the house for some time before they were discovered.

Their names are yet to be formally released.

But several people have confirmed the names to the Herald.

Beverley is listed in public records as being retired and Nick as a part-time worker.

Their family said they were not yet ready to speak about the deaths.

Police found the pair dead in separate rooms of the woman's home in Riccarton on Saturday night.

A relative had asked authorities to check on them after they were not able to make contact.

It is understood the bodies had been there for a number of days - possibly weeks.

Detective Senior Sergeant Colin Baillie would not be drawn on the circumstances but did confirm a homicide investigation has been launched following the discovery of the bodies.

"Specialist police teams and ESR are still carrying out a scene investigation at the address and expect it to be completed soon," he said.

"No one else is being sought in relation to the incident.

"Our thoughts are with the wider family and they are being supported by Victim Support."

The case has been referred to the Coroner but no further details about the victims' cause of death could be provided at this stage.

Their bodies were removed from the scene on Sunday night and post mortem examinations were carried out to ascertain their cause and time of death.

Police investigators remain at the scene, on the corner of Mona Vale Ave and Ayr Street.

When police arrived at the overgrown and ivy-covered property on Saturday uncollected mail was pouring out of the letterbox.

A moss-covered car was parked in the driveway - the concrete entirely engulfed by grass and weeds.

Google street view images show the same car in position in 2019.

The curtains in the house were mostly all drawn shut.

Since Sunday specialist police including forensic teams are at the scene and investigators are speaking to neighbours and those close to the victims as they try to piece together what happened in the house.

Residents said they had not seen the occupants of the house for some time.

But nothing seemed amiss at the house - which is generally overgrown and assumed by some people to be "abandoned" due to the lack of maintenance.

"I always thought this house was abandoned but had seen upstairs windows open a few times over the summer," said one woman.