A man thought to be Antony Waterlow was sighted in Randwick last week. (PR Image)

The 42-year-old had been the subject of a massive police manhunt after the stabbing deaths.

The search ended with a siege in bushland near Colo Heights in Sydney’s northwest on Friday afternoon, when he threatened to harm himself with a knife as police approached.

“After negotiations with local police the male placed the weapon down and surrendered to police,” head of the investigation Acting Superintendent Dennis Bray told reporters.

Without naming Waterlow, police said the 42-year-old Stanmore man was taken to Windsor Police Station and charged with two counts of murder and one count of recklessly inflicting grievous bodily harm.

He was refused bail and will appear in Parramatta Bail Court on Saturday.

Waterlow disappeared on the day his art curator father Nick Waterlow, 68, and 36-year-old sister Chloe Waterlow were found stabbed to death inside her Randwick home on November 9.

A two-year-old girl at the property also allegedly sustained a cut to her throat.

Waterlow was last seen leaving the property on the day of the killings.

For almost three weeks he remained at large, with fears he may harm himself and speculation he was sleeping in rough bushland.

In the end, it was a tip-off by a member of the public which helped end the manhunt, police said.

Someone spotted Waterlow walking in Colo Heights and went into a service station on Putty Road to confer with the shopkeeper.

Shopkeeper Sue Mahlenhouse said Waterlow had bought some groceries.

“Water, bread, just the essentials, oh, and a couple of meat pies,” she told the Seven Network.

Officers responded to the call and after a brief foot chase, Waterlow ran onto a nearby property and threatened self-harm with the small knife.

A day after the murders, police announced Waterlow was wanted for questioning and it emerged that he was a long-term sufferer of schizophrenia.

A major breakthrough came on Wednesday when police released CCTV footage confirming he was still alive.

The images, which showed him at an ATM in Randwick and at another inside a Parramatta Road hotel at Leichhardt, were widely circulated in the media.

Hundreds of mourners turned out last Friday to farewell Nick Waterlow at a funeral at Sydney’s St Marys cathedral.

Speaking during the service, Nick Waterlow’s partner Juliet Darling said he had loved all his children, including Antony “until the very end”.

Mother-of-three Ms Waterlow was farewelled at a service on Thursday last week.