A fourth person has been charged over a fatal shooting in Melbourne's north-west last month.

Kara Doyle, 24, died after she was shot at a house in Avondale Heights.

Mehmet Torun, 25, has been charged with murder.

A 21-year-old woman and 20-year-old man have been charged with being accessories to murder.

Today, detectives laid another accessory charge against a 43-year-old man from Avondale Heights.

He is expected to appear in the Melbourne Magistrates Court today.