Police say one suspect in Sarah Gatt body-in-bathtub case

Police believe one person is behind the suspected murder of a Melbourne mother, who lay undiscovered in her bathtub for eight months.

Sarah Gatt's body was found by police in her Kensington unit on January 3, and they believe the one-time aspiring model died in the four days to April 24, 2017, following a prolonged assault in her home.

Following a public appeal in March, police on Friday revealed the 40-year-old suffered trauma to her head and face, and believe the injuries are connected to her death.

Investigators believe one person is behind the mother-of-four's murder, with several others involved in hiding the incident and obtaining financial advantage from her death.