A 26-year-old woman has been arrested over the fatal stabbing of her boyfriend, who was aged in his 70s.

The elderly man was found dead in a home on Malmbury Drive, Meadow Heights, about 5.30am today.

A 57-year-old man and his 26-year-old daughter, Ruby Gold, were arrested at the scene, and are now being questioned.

Ruby Gold has been arrested over the fatal stabbing of her elderly boyfriend. (Supplied)

Detectives have spent the day combing the property. (9NEWS)

Neighbours told 9NEWS the elderly man was in a relationship with the 26-year-old arrested. (9NEWS)

9NEWS understands the father and daughter lived at the unit, and that the deceased was in a relationship with the daughter.

The victim did not live at the property, according to local sources.

Police have not laid any charges. The homicide squad has spent most of the day investigating at the property.

Police at the scene at Meadow Heights this morning. (9NEWS)

Meanwhile, investigations continue into another deadly stabbing in the suburb of Heidelberg Heights overnight.

A man was found with serious stab wounds at a Southern Road property about 12.50am.

The victim, who is yet to be formally identified, was treated by paramedics but died at the scene.

A timeline of this morning's deadly incidents in Melbourne's north. (9NEWS)

A man aged 48 who was at the home was arrested and is now assisting police with their enquiries.

It is believed the men were known to each other.