The mother of Jack and Jennifer Edwards, the teenage siblings shot by their estranged father in Sydney , has been found dead at her home in West Pennant Hills.

Olga Edwards was found dead by police around 10am on Wednesday, when they responded to a report from a neighbour with a concern for welfare at the same home where the bodies of the children, 15-year-old Jack and 13-year-old Jennifer, were found riddled with bullets in July this year.

Olga Edwards was found dead by police around 10am on Wednesday. LinkedIn

Ms Edwards' family, who live in Russia, have been notified. It is understood her mother had only recently returned to Russia from Sydney, where she had been staying with Ms Edwards to support her in the months since the shooting.

The cause of Ms Edwards' death has not been released by police.

After shooting the two children multiple times, Edwards then drove to his own home in Normanhurst and shot himself.

On Wednesday, Ryde Detective Superintendent David Waddell described Ms Edwards' death as a "tragic set of circumstances".

"Our police have been investigating [the shooting of Jack and Jennifer] since July 5 this year, when they responded to that address and found the two children deceased and just after 10 o'clock today they went back there...[to] the same home," he told Ben Fordham on 2GB.

Jack Edwards (right) tried to protect his sister Jennifer. Supplied

Detective Superintendent Waddell said Ms Edwards had been offered support from around the community, since the death of children but "unfortunately things took their toll".

"There are no suspicious circumstances. We will put a brief together for the coroner and that will form a part of the investigation that commenced in July," he said.

John Edwards killed his two teenage children before turning the gun on himself. Supplied

"[There are police] who have had involvement with the investigation and some of them are very personally attached and they are feeling it today, as are the family and wider members of the public."

When Ms Edwards arrived home from work on the day of the shooting in July, the north shore solicitor was met by police, ambulances and a helicopter after a neighbour saw the childrens' estranged father arrive at the home and heard gunshots.

At the time police sources close to the investigation said Jack died trying to shield Jennifer from their estranged father as he shot at them with handguns, described by police as "powerful".

Ms Edwards, 37, was treated for a severe case of shock before being released into the care of friends.

After killing his two children, Mr Edwards, 68, returned to his Normanhurst home where he turned the murder weapon on himself.

A manhunt ensued, culminating in police surrounding his Harris Road address before his body was found in the early hours of the morning.

At the Normanhurst property, investigators also found the two firearms used in shooting the children.

It was revealed by the Herald in the days after the shooting that Mr Edwards was granted a "Commissioner's Permit", allowing him to pursue handgun training at St Mary’s Indoor Shooting Centre.

The training is the first step towards getting a handgun licence and then a permit in NSW - despite his answers on a declaration form raising flags in the system.

with AAP

Support is available by phoning Domestic Family Violence Counselling Service 1800 737 732 Lifeline 13 11 14.