An indictment unsealed Tuesday charges Marshall, 83, with grand larceny, criminal possession of stolen property, forgery, scheme to defraud, falsifying business records, offering a false instrument for filing and conspiracy.
The top count, grand larceny, is punishable by up to 25 years in prison.
Marshall's former attorney, Francis X. Morrissey Jr., also was indicted on those charges.
"The indictment charges that Marshall and Morrissey took advantage of Mrs. Astor's diminished mental capacity in a scheme to defraud her and others out of millions of dollars," said District Attorney Robert Morgenthau.
A law enforcement source told the New York Daily News the one of the charges involves forging Astor's signature on a will that gave them control of her fortune.
The New York Post reports amendments to Astor's 2002 will shifted much of her fortune away from her favorite charities and directly to her son, Broadway producer Anthony D. Marshall.
Marshall and Morrissey had been accused in a civil suit by Marshall's son of misappropriating cash, real estate, securities and other property belonging to the socialite, who died in August at age 105.
Marshall's son, Philip, prompted the criminal investigation last year after he accused his father of neglecting Astor's care and stealing her money.
"It's hard to express my feelings at this moment," said Philip Marshall told the Daily News.
Marshall's son, Philip, prompted the criminal investigation last year after he accused his father of neglecting Astor's care and stealing her money. Astor died in August at age 105.
Anthony Marshall, a former diplomat and Tony award winning producer, has denied all allegations that he abused his mother's trust - saying that he cared about her more than anyone else.
Astor, known for decades as the grande dame of New York society and philanthropy, gave away nearly $200 million to institutions such as the New York Public Library and Carnegie Hall and to other causes.
In the final year of her life, the nasty family feud over her care was splashed all over the city's tabloids - including allegations that she was forced to sleep in a torn nightgown on a couch that smelled of urine while subsisting on a diet of pureed peas and oatmeal.
One of the tabloids Tuesday morning ran the headline "Crook Astor."
Astor's friends, Annette de la Renta, the wife of designer Oscar de la Renta, and David Rockefeller, the banker and philanthropist, both signed affidavits supporting Philip Marshall's claims.
The grand jury heard testimony for almost a month on how Marshall and Morrissey managed Astor's estate and documents related to it. Philip Marshall, a professor at Roger Williams University in Rhode Island, testified before the grand jury, according to his spokesman, Frazier Seitel.