The bodies, some covered with blankets, were found on Friday in different rooms of the Victorian-era house in the upscale Chicago suburb of Evanston.

Investigators continued to probe how the frail nonagenarian could have kept the bodies at home, but no charges were filed.

Neighbours of Ms Margaret Bernstorff knew she was a pack rat, but none imagined that along with the old furniture and stacks of old newspapers, she was storing the three decaying bodies of her siblings.

'I'm shocked. I think we're all shocked', said Mr Allan Redmond, an Evanston contractor who had become friendly with Ms Margaret Bernstorff after doing repairs on her home.

'A few weeks ago I asked her about her sister (Anita) because it had been a long time since I'd seen her. She said that her sister was sick and upstairs, but I couldn't have imagined something like this.'

The Bernstorff family had lived in the historic Evanston neighbourhood since at least the 1960s, when Ms Margaret Bernstorff's father, Frank, was an assistant professor of German studies at Northwestern University.

Prof Frank Bernstorff died in 1966 and his wife, Lilian, died eight years later.

The home has since been occupied by all four of their children at different times, police said.

Some neighbours occasionally checked in on Ms Bernstorff, bringing food and groceries the woman didn't always warmly accept.

'She could be stubborn and she didn't take help a lot of the time', Mr Redmond said.

The 90-year-old has been placed in a senior care facility. -- AFP