The son of a Melbourne mum murdered almost 40 years ago is angry police bungled the investigation by mixing up DNA evidence.
Victoria Police have admitted DNA taken from bloody pillowcase, and used to rule out priest Anthony Bongiorno as a suspect,came from an unrelated case.
Maria James, 38, was killed in 1980 in her Thornbury bookshop and the priest, who's since died, was a key person of interest.
Her sons Mark and Adam were 13 and 11, respectively, when she died.
The siblings have long suspected the Catholic priest was involved because he had abused Adam as a child.
Adam James recently detailed his abuse to an ABC Trace podcast looking into the case.
"I remember he said to me 'Adam, can you come with me and I don't want you to tell your mum or Mark'," he told the ABC.
Bongiorno took him into a back round and abused him before Ms James came to collect her son, Adam said.
Mark James says he's angry around the latest turn in the Victoria Police investigation.
"I am actually angry. I feel quite indignant," he told ABC television on Thursday.
But despite the disappointment, Mark's also relieved.
"When I was originally told that Father Anthony Bongiorno had been eliminated through some form of DNA-type testing, I found it difficult to accept," he said.
"But now that police have confirmed that Father Bongiorno and others are actually not eliminated, I'm feeling some relief."
Victoria Police Assistant Commissioner Steve Fontana the DNA mix up was the result of a human error made three decades ago.
"This was human error," he told reporters on Thursday.
"Basically, this means we need to go back and re-examine all the exhibits from the Maria James investigation."
Persons of interest previously ruled out of the investigation would now be re-examined.
"We've got to go back and ... see whether we can actually identify whether the offender has left any trace evidence behind,"Mr Fontana said.
"We don't have a profile on the suspect at this stage."
Mark is seeking clarification about when the unrelated DNA was introduced to the investigation.
"I accept it was human error but the clarification I am seeking was, specifically, did this interference occur before Father Bongiorno became a suspect in this case?"
Mr Fontana said the error was discovered this year after a cold case inquiry into Ms James' death began.
The James family say they have applied to the Victorian Coroner to re-examine the case as well.
Mr Fontana does not expect the exhumation of bodies, including the remains of Father Bongiorno, will be needed as a new investigation gets underway.
The podcast into the case
ABC investigative reporter Rachael Brown, the host of the Trace podcast into the case, said police could now start moving on the case now that such a roadblock has been removed.
"Perhaps suspects that were elimated that shouldn't have been can re-looked at," she told SBS World News.
"What I'd really desperately hope is they go back and re-test her exhibits."
Ms Brown said the podcast was been inundated with fresh leads that she's been trying to pursue.
"The case was evolving as Trace has been going to air," she said.
