Former federal MP Phil Cleary has blasted the police investigation into the murder of Melbourne mother and bookstore owner Maria James seven years before his sister was killed by Peter Keogh.
Coroner Caitlin English on Thursday delivered an open finding into Ms James' murder, but identified Keogh as one of two significant persons of interests.
Catholic priest Anthony Bongiorno was also named. Both men are dead.
"My sister is dead because those police didn't properly investigate Keogh," Mr Cleary told AAP on Friday.
Ms English's findings criticised police blunders in their investigation of Ms James' murder, including their failure to preserve crucial evidence.
Mr Cleary gave evidence about Keogh at the inquest. The killer stabbed his sister to death in 1987 outside the kindergarten she worked at after she ended their relationship.
Mr Cleary, a provocation law reform champion, says police didn't listen to several women who had information that could potentially link Keogh to Ms James' murder.
"The moral of the story, given the ongoing crisis of violence against women, is that we can no longer depend on men in the police force," he said.
"We have to have more women involved. The failings in this investigation are part of a systemic failure in the way we understand and deal with men's violence against women."
Ms James was stabbed 68 times in June 1980 at her Thornbury home and bookshop.
Ms English said Keogh, who was known to "hate women", lived in the area and worked night shifts, could have been at the bookshop when Ms James was murdered about midday.
She also noted Keogh had threatened to do to Ms Cleary "what I did to the bookshop woman".
Ms English found investigators had not properly considered Keogh a suspect.
"Mr Keogh perpetrated violence against many women. He had opportunity and proximity to the area, and he may well have known Mrs James and been aware she was alone in the book shop."
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