Officers were called at 6.49pm on October 1 following reports of a crash in Brixton Road near the junction with Handforth Road.
The pedestrian, named by police as Safia Ali, was first hit by the tow truck, which did not stop, then struck by a car.
The driver of the car stopped at the scene, police said.
Despite the efforts of paramedics, Ms Ali, who was in her 50s, was pronounced dead at the scene.
Her next of kin were informed and are being supported by specialist officers, police said.
A man who was arrested for failing to stop at the scene of an accident and causing death by dangerous driving, has been bailed pending further inquiries.
Any witnesses or anyone with information, such as dash cam footage, are asked to call police on 101, reference CAD 6064/01Oct24 or the witness number on 020 8285 1574.
