The son of a murdered Melbourne mum says he is disappointed about the police bungling of DNA evidence in the investigation into her death.
Victoria Police on Thursday admitted to introducing DNA evidence from another crime scene into its investigation of Maria James' 1980 murder in a Thornbury bookshop.
Local priest Anthony Bongiorno, who is now dead, was ruled out as a suspect based on DNA from a bloody pillowcase.
But that pillow case was introduced from an unrelated crime scene, Victoria Police Assistant Commissioner Steve Fontana confirmed at a press conference on Thursday.
"I am simultaneously quite disappointed but I have a sense of relief as well," Mark James said on ABC television on Thursday.
"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 but now that police have confirmed that Father Bongiorno and others are actually not eliminated, I'm feeling some relief."
Mr Fontana told reporters the mistake came from human error that occurred three decades ago.
"Unfortunately, it was only discovered this year, when we were running through our homicide investigation, reopened the case, re-examining exhibits, as well as forensics," Mr Fontana told reporters.
"Basically we don't have a profile on the suspect at this stage.
"So, basically we've got to go back and, you know, look at all the exhibits that were available and have been held in relation to this particular case, to see whether we can actually identify whether the offender has left any trace evidence behind."
© AAP 2017 Photo credit: AAP Image/David Crosling