Police in two states are investigating the separate but similar discoveries of dead men.
Two men, believed to be aged in their 70s and 80s, were found dead in a home in inner-city Sydney on Thursday.
In Queensland, police found two dead men, aged 65 and 56, during a welfare check at a unit complex on the Sunshine Coast on Friday.
It is unclear when the men died.
The men found in the terrace home on Cleveland Street at Surry Hills are believed to have died in the house but at different times within the past month, detectives said.
They were found in separate rooms of the property.
A 63-year-old woman who also lives there has been spoken to by investigators but no charges have been laid.
Police are investigating how and when the two men died.
Separately, police in Queensland are investigating the deaths of two men at a unit complex on Kingsford Smith Parade at Maroochydore.
A neighbour called police to conduct a welfare check before the discovery, a police spokesman said.
The men have been identified as a 65-year-old Maroochydore man and a 56-year-old from nearby Mountain Creek.
The unit remained a crime scene on Saturday as police investigated their deaths.
Anyone with relevant information or CCTV footage is urged to contact police.
