Casey Johnson died in rat-infested house

Heiress Casey Johnson lived her final days in a rat-infested house and her squalid home was about to be repossessed.

Casey was heavily in debt at the time of her death and could not pay her bills, despite standing to inherit the massive Johnson & Johnson fortune, the New York Post reports.

Worried about the socialite's drug taking and increasingly erratic behaviour, Casey's parents had cut her off financially in the hope that she would mend her ways.

The 30-year-old was found dead in her Los Angeles home on Monday.

It is believed she died three days earlier. Police said there was no sign of trauma on her body and there was no foul play involved.

Friends told The Post Casey's life had spun out of control and she had let her home fall into such a state of filth that the grounds were overrun by vermin.

"There are dirty dishes everywhere and rotting food," an unnamed friend of Casey's told the newspaper.

"There is graffiti on the walls. The pool looks like a swamp."