A 23-year-old man arrested in connection with the murder of Marie Conlon, whose remains lay undiscovered for almost three years, is also being questioned about fraud and theft.
The Irish News understands that man lives in the same area of west Belfast as the 68-year-old.
Police have launched a murder inquiry following the results of a post-mortem examination but believe Ms Conlon may have been killed around January 2015.
Her remains were discovered last Friday by police who forced their way into her flat at Larkspur Rise, off the Suffolk Road.
Her family last night described her as a "very independent person" and said they were "heartbroken" by her death.
It is understood Ms Conlon was not married and had no children
Police said her remains were found in bed and it was "apparent that she had lain undiscovered for some time."
Detectives last night continued to question the 23-year-old about Ms Conlon’s murder and also on suspicion of theft and fraud.
Asked if they were assisting with the police investigation, a spokesman for the Department for Communities - which is responsible for the benefits, pensions and welfare system - said: "The department does not comment on ongoing police investigations".
Sinn Féin councillor Séanna Walsh, who knows the woman's family, said they are "distraught" about what had happened.
"The family are devastated. They are shocked. They are grieving.”
He added: "One of the tragedies of modern living is that in areas like this you don't have the same sense of connectedness you would have had if she had have lived in the estate.”
In a statement last night, Ms Conlon's siblings said they were "shocked and heartbroken" by her loss.
"The tragic circumstances of her death make it all the more difficult to comprehend and accept," they said.
"Marie was very much loved by her family and will be mourned greatly. She was a very independent person.
"Numerous attempts had been made to contact her in person, and by other means, over the course of the past two years but at no point were suspicions raised that she had been deceased.
"It is only with hindsight that the unimaginable now seems possible."
The family said they had been working with the PSNI to "bring this devastating situation to an end".
"We hope and pray that justice will be done and ask for privacy as we grieve the loss of our sister," they said.
