Mechanic charged with great-grandma death

A heavy-vehicle mechanic accused of killing a great-grandmother at her front door had known his alleged victim's family for a couple of years, police say.

Rodney Boatswain, 63, was arrested on Monday, almost three months after Helen Dawson Key was shot in the head at her Toongabbie home in western Sydney.

Mrs Dawson Key had been due to play a social bowls game on November 20, but a friend found the 75-year-old's body when she went to pick her up.

Police allege Boatswain shot Ms Dawson Key the night before.

It is alleged Mr Boatswain, a married man with adult children, had known the family for a couple of years and the crime was premeditated.

A motive has not been revealed but detectives have ruled out robbery and a case of mistaken identity.

Boatswain, of Glenwood, was breathing heavily as he appeared briefly in Blacktown Local Court on Monday afternoon.

He did not apply for bail and will appear in Parramatta Local Court in April.

Mrs Dawson Key was a long-time member of the Toongabbie Sports Club and had no known enemies, leaving police initially baffled as to why someone would target her.

Homicide detectives released a photograph of a maroon-coloured Toyota Camry caught on CCTV near her home about the time of her death.

Police allege the car was in Mr Boatswain's possession.