Updated

The son of philanthropist Brooke Astor was accused Tuesday of plundering his mother's $198 million estate and conspiring to have the Alzheimer's-stricken socialite sign a new will leaving her fortune to him.

Anthony Marshall, an 83-year-old Broadway producer, was charged in an indictment unsealed Tuesday and pleaded not guilty at an arraignment. His former attorney, Francis X. Morrissey Jr., was indicted on similar allegations.

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," District Attorney Robert Morgenthau said.

As early as 2001, Astor's doctors had told Marshall that his mother suffered from Alzheimer's disease, that her ability to understand complex issues was limited, and that her condition would worsen, Morgenthau said.

Three years later, the prosecutor said, Marshall and Morrissey conspired to have Astor's attorney fired, and to have her sign an updated will that left Marshall virtually everything.

Morrissey also is charged with participating in the forgery of Astor's signature on that will, Morgenthau said. He didn't explain how the signature was forged.

Marshall's current lawyer, Kenneth Warner, said in a statement that he and his client are confident Marshall will be exonerated.

"Tony Marshall faithfully and effectively managed his mother's affairs for more than 25 years, increasing the value of her investments from $19 million to $82 million," Warner said. "Brooke Astor loved Tony, her only child, and whatever he received was in accordance with her wishes."

Marshall was released and ordered to appear at his next court hearing on Jan. 30.

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. If convicted of the most serious charge, grand larceny, he could be sentenced to 25 years in prison.

Marshall and Morrissey also were accused in a lawsuit filed by Philip Marshall of misappropriating cash, real estate, securities and other property belonging to Astor.

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, Carnegie Hall and 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.

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. Though he denied the claims, Anthony Marshall agreed in October 2006 to step aside as his mother's guardian.

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.

The grand jury investigation had already brought a halt to substantive proceedings in the civil dispute over Astor's estate. Anthony Marshall had supported a 2002 will and its codicils, or additions, which benefit him at the expense of the charities Astor named. Others, including Philip Marshall, contended a 1997 will was the last one she was competent to sign.