Almost 44 years after Maria James was brutally stabbed to death in her Melbourne bookshop, her two sons hope a $1 million reward will finally unmask the killer.
Ms James' killer stabbed her 68 times on June 17, 1980, in what her son Mark described as a "ritualistic'', violent and frenzied attack.
And he believes people know the killer or killers but have stayed quiet to protect the reputation of a priest and his church.
"Our mum was murdered on the same day she'd gone to our nearby Catholic church to report the sexual assault of my brother by a priest named Father Anthony Bongiorno," Mark James told reporters on Friday.
"We believe people have stayed quiet to protect the Catholic Church but by speaking up now, you are doing the right thing and you'll be rewarded.
"You're doing what God would want you to do."
A coroner in 2022 found two men who have since died - Father Bongiorno and Peter Keogh - remained significant persons of interest in the case following a 17-day inquest.
Victoria Police on Friday announced a $1 million reward for information to help solve the case.
Detective Inspector Dean Thomas said people previously identified as suspects had remained as such but there was still not enough evidence to charge anyone.
He also acknowledged the killer or killers could be dead.
"But, if that is the case, again, please bring that information forward to us," Det Insp Thomas said.
"If we can identify the person responsible, and if that person is now deceased, we can still take that matter back to the Coroners Court and put that fresh evidence forward so that the coroner can make any determination or recommendations that they feel fit at that point."
Police have said the Director of Public Prosecutions would consider granting indemnity to those who revealed the identity of the person or people behind Ms James's murder.
For her sons, the mystery surrounding the murder of their mother has plagued them for 44 years and they hope the $1 million reward will help someone provide information that will end their torment.
"It's been a hard, traumatic time for both of us," Adam James said.
The brothers had lived with their mother in the bookshop on High St, Thornbury, in Melbourne's northeast, which also served as their home.
On the day of the murder, she had phoned her ex-husband John to talk but then told him to "hold on", as someone was in the shop.
John could not make out the conversation but knew something was not quite right, police said.
"He did get the feeling from what he could hear that it was not a good conversation," Det Insp Thomas said.
John went to the shop to check on her and found the front door locked but with the "open" sign still out.
He forced entry and found her dead in her bedroom with her hands tied.
Soon after, John discovered the bookshop's front door was unlocked - suggesting someone left when he arrived.
Two people reported seeing a man running away from the crime scene. One was depicted in police sketches.
Det Insp Thomas urged people not to have preconceived ideas about the case, and said it could be that the killer was not someone previously identified as a suspect.
The most recent inquest into Ms James' murder found major investigative blunders in her case but could not identify her killer, while an inquest in 1982 returned an open finding.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028