Homicide detectives are knocking on doors in Perth's northern suburbs in a bid to chase down leads on a decades-old murder.
In March 1999, Andrew Podpinka's wife and daughter found him stabbed to death in his home in Morley when they returned from shopping.
The 43-year-old was found in the master bedroom with extensive wounds to his chest and back.
The West Australian government has offered a $250,000 reward for information leading to a conviction, and people who come forward may be granted immunity from prosecution.
Detectives on Wednesday will knock on doors on a nearby Morley street as part of their renewed investigation.
Authorities are hoping to identify a man who contacted police from a phone box several days after Mr Podpinka's body was found. He did not leave any contact details but police believe he had information that could aid their investigation.
The no-longer existent phone box was less than two kilometres from Mr Podpinka's home.
A woman who called Crime Stoppers in June 2006 also provided useful information.
"The information was quite detailed and investigators believe she may have intimate knowledge of the offence and offender," WA Police said on Wednesday.
"Police ask that the man and the woman again make contact, either in person or anonymously via Crime Stoppers, to help investigators further their inquiries."
Mr Podpinka's wife Margaret last year urged those involved in her husband's death to "take a moment to reflect on what you did to our family".
"How can you live with yourself? How can you sleep at night," she said.
"How can you look your own family in the eyes keeping such a dark secret for so long."
Mr Podpinka was a slight man with some physical disabilities. His wife said he would have had no chance fighting off his attacker.
"I'm hoping someone, somewhere knows something," Mrs Podpinka said.
"We do need public help to solve this cold case and make the community a safer place to live."