A mentally ill woman was discovered in a "mummified, almost skeletal state" after lying dead for more than three years in her flat, her family say.
Laura Winham, 38, was "abandoned and left to die" by the NHS and social services before her body was found by her brother in May 2021, they claim.
She is thought to have died in November 2017 after being referred to social care twice in the previous years.
The NHS and Surrey Police have been contacted for comment.
Surrey County Council said it was a "truly tragic case" and that it would provide information for an upcoming inquest into the death.
Ms Winham, who had schizophrenia, lived in social housing in Woking, Surrey, and had become estranged from her family.
In 2014, a referral was made to Woking Community Mental Health Recovery and her GP, flagging that she appeared to have "untreated mental health issues", her family said. This was not followed up.
After visiting Ms Winham in October 2017, in what was probably the last time anyone saw her alive, Surrey Police officers reported to Surrey County Council that she had been "self-neglecting, had little food, and appeared unaware of how to access local services for help".
Shortly after this visit, the markings on Ms Winham's calendar stopped. One of the last entries read: "I need help".
Her sister Nicky said despite the "warning signs" about her deteriorating mental health, "everyone seems to have turned a blind eye".
She added: "Everybody who was in contact with Laura and had a duty to her at some stage simply wiped their hands of her and forgot her.
"She was abandoned and left to die.
"It's just heart-breaking to think of how she lived in her last few years, unable to ask for help, without anyone there for her."
Iftikhar Manzoor, of Hudgell Solicitors, who are acting for the family, said: "Laura was referred to adult social care teams twice, firstly in 2014 and then by the police in October 2017.
"Assessments of her needs were not carried out. Without doubt these were clear missed opportunities to intervene and carry out a welfare check."
A spokesperson for Surrey County Council said it was a "truly tragic case".
"It's important that every aspect of this complex case is reviewed and we're committed to participating fully in the inquest process," they added.
They confirmed they would provide any information needed to support the coroner's inquiries.
