The family of a woman beaten to death by her roommate at a Bronx public hospital plans to sue the city for $20 million, alleging staff was negligent, withheld information and failed to keep her safe.

Cynthia Vann, 55, was undergoing liver treatment at Lincoln Hospital in September when police said she was attacked by 44-year-old Racquel Haughton. The beating left Vann in critical condition for more than two weeks before she succumbed to her injuries. Officials ruled her death a homicide and Haughton was arrested and charged with manslaughter and assault in October, more than a month after the incident.

Vann’s relatives claim hospital staff failed to protect her from Haughton and were not forthcoming about why her condition deteriorated so gravely. The family is expected to announce Thursday they are filing a notice of claim against the city and its hospital agency as the first step in mounting a lawsuit, according to Rev. Kevin McCall, a spokesperson for Vann’s loved ones.

“They would just tell me about her condition medically, but they didn't tell me what was the reason for the head trauma,” Vann’s daughter Tanesha Vann previously told Gothamist. “When I found out she was in emergency surgery, I was shocked.”

John Elefterakis, the family’s attorney, said he hopes the filing will get city officials’ attention.

“We intend to litigate this matter and will use every tool at our disposal to uncover the truth about what occurred and the failures that led to Cynthia’s tragic death,” he said in a statement.

“Somebody needs to answer for this,” McCall said.

Lincoln Hospital is seen in the Bronx on Jan. 19, 2011.

New York City Health and Hospitals did not immediately respond to a request for comment early Thursday. After Vann’s death, a spokesperson for the agency said in a statement that Lincoln Hospital was “committed to the safety of its patients, staff and visitors.”

Haughton is being held at the Rikers Island jails and is due back Thursday in Bronx Criminal Court. Her lawyer was not immediately reachable for comment.

McCall said Vann’s family is struggling to cope with her death and the questions surrounding it.

“ [Tanesha] went from speaking to her mother every day to not speaking to her — to attempting to dial a number and knowing that her mother's not there,” he said. “Her son, he cries on and off. She asks him, ‘What's wrong?’ And he just says, ‘I miss my grandma.’”