Warning: This post mentions suicide and may be triggering for some readers.
In June, mail began piling up outside an apartment in south-west Sydney.
Rental payments had been missed and an eviction notice for the Canterbury apartment had been filed.
Inside, two Saudi Arabian sisters, both in their twenties, were dead in their beds.
Police officers who were responding to a concern for welfare report, found the bodies of 24-year-old Asra Abdullah Alsehli and 23-year-old Amaal Abdullah Alsehli in separate bedrooms on June 7.
Police believe the sisters died a month earlier in May. But how they died remains a mystery.
There were no visible signs of a break-in nor any injuries to their bodies.
Two crucifixes were also found on the floor of one of the bedrooms, a worker with access to the apartment told the ABC.
Several weeks later, police are treating the deaths as "suspicious".
"We have been unable to determine the exact circumstances surrounding Asra and Amaal's deaths," Detective Inspector Claudia Allcroft said last week, explaining police are still waiting on the coroner's report.
Watch: Detective Inspector Claudia Allcroft addresses media about Asra and Amaal's deaths. Post continues below.
Appealing for information from the public, Det Insp Allcroft said any piece of information could hold the key.
"Detectives are interested in speaking with anyone who may have seen or who may have information about the women's movements in the days and weeks prior to their deaths - which we believe occurred in early May," she said.