The state's crime assistant commissioner Michelle Fyfe said they wanted the public's help.
"We are seeking public assistance regarding Dorrough's movements across Australia and even in New Zealand over the past 20 years."
Dorrough was a suspect in the 1997 disappearance of a 21-year-old woman in the northwest Australian beach resort town of Broome and he was charged with the 1998 murder of a 29-year-old prostitute in Sydney. He was acquitted at trial.
West Australian police spokeswoman Ros Weatherall told the Herald on Sunday last night Dorrough was in Auckland between May 2006 and August 2006.
Dorrough lived in almost every Australian state and had many jobs before his death aged 37, including as a marine technician, sheet metal fabricator, commercial diver, air system technician, welder and postie, Weatherall said.
She did not know where or what Dorrough's occupation was when he was in New Zealand.
The state's special crime squad had contacted police in the places where Dorrough had lived or visited and so far they had been unable to link him to any unsolved crimes.
A New Zealand police spokesperson said: "We will assist the Western Australian police if requested and evaluate if action is required in regard to New Zealand crimes when we know more facts."