A couple found in the burnt out remains of a house south of Brisbane were not killed by fire, with post-mortem results showing "evidence of violence".
Police say they have "ruled nothing out" as they investigate the deaths of the couple - a 68-year-old woman and 73-year-old man - who were discovered in a Collingwood Park residence's charred remains on Sunday morning.
Acting Inspector Heath McQueen on Friday described the investigation into the suspicious deaths as "complex" and expected it to continue into next week after establishing an incident centre at an Ipswich police station.
"Post-mortems have been conducted ... I am unable to go into details other than confirming their deaths are suspicious, and not contributable to the fire, with evidence of violence," Acting Insp McQueen said.
"This is a complex investigation, in which all possible options as to the cause of their deaths is being fully explored.
"We have ruled nothing out at this stage."
He said "extensive" forensic tests were continuing at the Hannant Street home which has been declared a crime scene.
The couple - who have been identified by colleagues on social media as Joe and Christine Stephan - were found in the lower level of the home which quickly caught alight early on Sunday.
"They were both so genuine, helpful and caring [people] who always offered their help even when not asked," a Facebook post from Mr Stephan's work colleagues Rudy and Alma said.
Emergency services were first called to the home about 1am but by then it was well alight with smoke billowing from the roof.
Ipswich detectives are leading the investigation - code-named Operation Verdite - with assistance from homicide, forensic and scientific officers.
"Complex and detailed forensic examinations, as well as investigations and interviews by detectives, will continue for some time," Acting Insp McQueen said.
"I understand the interest from the media and the community, and rightly so, however, to maintain the integrity of the investigation, I am unable to provide any further details or updates at this time."
He said anyone with information should contact police.
Australian Associated Press
Sign up for our newsletter to stay up to date.