The code of silence pervading Canberra's criminal underworld is still frustrating police investigations into the brutal murder of Susan Winburn almost nine years after the crime.
Winburn, 45, was found strangled in the bathtub of her Gordon home on January 13, 2004.
Police believe her murder was a burglary gone wrong and that she may have been killed to prevent her identifying those responsible.
Criminal investigations detectives have spoken of their frustration at not being able to solve the murder.
An inquest into the death identified four people of interest: Ian ''Maggilla'' Kelly, Neil ''Dori'' Kelly - both serial offenders - Joel Ross and Leanne Madden
Detective Leading Senior Constable Rick Gill said a ''code of silence'' was preventing people coming forward.
He said those with information feared retribution and that they would lose their reputation among Canberra's criminals.
''I'd take this opportunity to really urge anyone with information on Susan's murder to basically break this code of silence, put themselves in Susan's family's position and contact Crime Stoppers,'' Senior Constable Gill said.
The reward for information on the crime doubled to $500,000 in September, a move that has attracted more than a dozen tip-offs.
Those tip-offs have provided some positive results for detectives investigating the crime.
Senior Constable Gill has been in regular contact with Winburn's mother.
''There's good days and bad days, I suppose,'' he said.
''Obviously the Christmases and the birthdays and, unfortunately, the anniversary of Susan's death are the hard times,'' he said.
''But she's a very strong lady and she continues to battle on.''
Anyone with information is urged to contact Crime Stoppers on 1800 333 000. Police will consider indemnity from prosecution for any accomplice who comes forward with information.