Homicide Squad detectives are investigating a death which occurred in Heidelberg West last night.
Police were called to a Liberty Parade address following reports of an aggravated burglary about 8pm.
It is believed a man broke into a house before assaulting a female occupant inside.
The woman died at the scene.
Another man, believed to be known to the victim, attended the property to render assistance and restrained the alleged offender.
He restrained the man till police arrived and the alleged offender was then taken to hospital and remains there under police guard.
The exact circumstances surrounding the incident are still to be determined and the investigation is ongoing.
Anyone who witnessed the incident or who has information is urged to contact Crime Stoppers on 1800 333 or submit a confidential crime report at www.crimestoppersvic.com.au