The body of a woman was discovered inside a furniture chest at a Gold Coast unit where a man's body had also been found.
The 53-year-old man's body was found at the apartment on Labrador St, Labrador, about 10.20am on Friday.
Officers who arrived on the scene later found the body of a 48-year-old woman in the same unit.
Gold Coast District Detective Inspector Chris Ahearn said early indications were the man may have been responsible for the woman's suspicious death.
Police believe the pair were in a relationship for about 10 years.
"There is some suggestion that the male person was also a carer for the female," Det Insp Ahearn told reporters on Saturday.
"One of the lines of investigation is into the medical condition of the female person, prior to her tragic death."
There were no domestic violence orders in place and the couple was unknown to police.
No third parties are being sought at this stage.
"It is a tragic event," Det Insp Ahearn said.
"We are pouring significant resources into an expansive investigation of it because we are intent on getting answers for the family as to why and how these two people have died."
The woman is yet to be formally identified.
Both bodies will undergo post-mortem examinations on Saturday to give an exact timeline for their deaths.
Det Insp Ahearn said the decomposition of the bodies indicated they had been dead since at least last weekend.
"We believe the female person is in a more advanced state than the male," he said.
A report is being prepared for the coroner as forensic specialists continue to comb through the unit.
Police are urging anyone who saw anything suspicious at the Sapphire apartments complex in Labrador to contact Crime Stoppers.