Police believe a Melbourne grandmother who was murdered in her home nine years ago knew her attacker.
A $1 million reward is being offered to solve the murder of 69-year-old Jeanette Moss, who was found dead in her Middle Park apartment on the morning of January 15, 2014.
There were no signs of forced entry at the property and a number of drinking glasses were left on the kitchen counter, Detective Acting Inspector Paul Scarlett said.
"We feel that it is very likely that Jeanette knew her attacker or attackers, or at least felt comfortable enough to allow those people into her home," Mr Scarlett told reporters on Wednesday.
Ms Moss's son Derham said he couldn't believe that someone who knew his kind, generous and happy mother would kill her.
"She wouldn't have had any enemies," he told reporters.
"To think that someone that she may know does something like that and then can go on living a life is simply extraordinary to me."
Officers have trawled through thousands of hours of CCTV footage to piece together Ms Moss's movements before she was found dead.
The day before, she ran a number of errands in her local area in her green 1997 BMW sedan.
An inquest later found she likely died between 12.47pm and 2.52pm on January 14.
Police have ruled out a number of persons of interest although they are still investigating several theories on what happened to Ms Moss, Mr Scarlett said.
He hoped the $1 million reward would encourage anyone who knows something to come forward.
"We have only come so far with this investigation and we just need that one key piece of evidence," Mr Scarlett said.