The crime scene established that there was no sign of forced entry. Nothing was stolen and there was no indication of Marea putting up a fight. This led police to believe the murderer was known to her.
In 2006, Marea's former son-in-law, Joseph 'James' Unumadu was charged with her murder, but was acquitted by a jury in 2008.
"When we went to court we all believed we'd get justice for Mum, but deep down I had a feeling of dread," Jeff says.
The trial ended with no further suspects, and nobody [was] found guilty. Esther says it meant "dealing with a grief" that was never at an end."
For Jeff, it fuelled a decades-long campaign for the truth which has recently culminated in an Australian True Crime podcast and Sky News documentary.
The 20th anniversary of Marea's death comes as Victorian police have increased the reward for information into her murder to $1 million.
"It was so symbolic of our larger struggle. All the family have been so inspired by this push to get justice," Jeff says.
"Several senior police have told me they believe the case is solvable and I keep reminding myself how many people are supporting us and committing to this. We have achieved a lot and Mum would be so proud," Jeff continues.
"Now I have to sit back and rely on the system that it will make someone accountable."
Jeff is about to take Esther and his youngest daughter Bella to visit Marea's Italian homeland. When they return, Esther will resume the fight for justice.
Inspired to become a criminologist as a result of her childhood experiences, Esther says it's now her turn.
"Having a murderer on the streets for 20 years, it's unacceptable especially the violence that Nona faced in her final moments," she says.
"It's time to give [Dad and Aunt Ronda[ a break. I'm the next generation and I won't let this rest."
Do know something? Anybody with information is asked to contact Crime Stoppers or visit crimestoppers.com.au