(CNN) -- A jury in Manhattan found the son of Brooke Astor and one of his lawyers guilty Thursday of scheming to bilk millions of dollars from the late philanthropist's estate.



Anthony Marshall was convicted of bilking millions of dollars from the estate of his mother, Brooke Astor.



The verdict, returned on the 12th day of deliberation, ended a six-month trial that featured as witnesses a Who's Who of New York's social elite.



Anthony Marshall showed no visible reaction as he was found guilty of 14 of the 16 counts against him. His wife, Charlene, who many believed fanned his greed and instigated his mistreatment of his elderly mother, also did not seem to react.



Marshall was convicted of the most serious charges -- first-degree grand larceny and scheming to defraud. One of the most serious convictions involved Marshall giving himself a $1 million-a-year raise for handling his mother's affairs, said Assistant District Attorney Joel Seidemann.



Marshall's former lawyer, Francis Morrissey, was convicted of all five counts against him, including forgery and scheming to defraud Astor.  Watch Marshall's attorney vow to appeal »



"These defendants, two morally depraved individuals, preyed on a physically and mentally ill 101-year-old woman to steal millions of dollars -- dollars that she had intended to go to help the lives of ordinary New Yorkers," Seidemann said, echoing his closing argument to the jury.



Astor, who had Alzheimer's disease, was 105 when she died in August 2007.



The prosecution called nearly 70 witnesses -- Henry Kissinger, Graydon Carter, Barbara Walters, Vartan Gregorian and Annette de la Renta among them.



Prosecutor Seidemann called the case "disturbing," and said the trial told the story of "how a son, an only son, would stoop so low to steal from his own mother in the sunset years of her life in order to line his own pockets and the pockets of his wife."



Marshall, who is free on $100,000 bail, faces a maximum 25 years in prison when he is sentenced on December 8. Morrissey faces up to seven years in prison.



Author Meryl Gordon, who has followed the Astor story for years, was in the courtroom when the jury returned its verdicts.



"It was an incredibly bad, intense time," she said from her cell phone before hopping on a subway. "I was a little surprised that Charlene did not get visibly teary. I guess she was braced for it."



Marshall, Astor's only child, was indicted on criminal charges in 2006. The case kicked off a tabloid feeding frenzy that fostered headlines such as "Bad heir day," "Mrs. Astor's disaster" and "DA's kick in the Astor."



Through her late husband's Vincent Astor Foundation, Brooke Astor is credited with giving New York, where the Astors made their fortune, about $200 million.



The Astor Foundation gave millions to New York cultural jewels -- including the Metropolitan Museum of Art and the New York Public Library -- as well as lower-profile programs.



Astor was often quoted as saying, "Money is like manure; it's not worth a thing unless it's spread around."



"Mrs. Astor stood in New York as a symbol of generosity. And this trial stands as a landmark for the nefarious impact of money and greed," said her longtime friend, Vartan Gregorian, president of the Carnegie Corporation of New York.



"It will in many ways tarnish her memory," he said. "It's a sad day, but at the same time, one good thing that will come out of this -- that Mrs. Astor would approve of -- is that the elderly cannot be abused."



The case began when Marshall's son, Philip, filed a petition in 2006 asking the court to appoint a guardian for his grandmother. The court documents alleged "elder abuse" and were intended to remove Anthony Marshall's control of her affairs and transfer care to Astor's dear friend Annette de la Renta.



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