In court papers obtained by the New York Daily News, Philip Marshall claims that his father, Anthony Marshall, refuses to spend money on Astor's care and would not even allow her to have a new outfit for her birthday.
Former Secretary of State Henry Kissinger, former Chase Manhattan Bank CEO David Rockefeller and Annette de la Renta, wife of designer Oscar de la Renta, have filed affidavits backing him up.
Philip Marshall has asked a court to replace his father as Astor's guardian with Annette de la Renta and the JP Morgan Chase Bank.
Anthony Marshall, 82, is a World War II veteran who participated in the invasion of Iwo Jima and later served in the CIA and became a Tony Award-winning producer on Broadway.
In court papers, his son says that Anthony pays himself $2.3 million a year as his mother's caretaker, while she receives $2 million from the estate of her late husband, Vincent Astor.