Anthony Marshall, the 89-year-old son of the late New York philanthropist and socialite Brooke Astor, was granted his release from jail on medical parole.

Marshall, who suffers from Parkinson’s disease and other ailments, was convicted in October 2009 of grand larceny and other charges for changing his mother’s will while she was incompetent. He was sentenced to one to three years in prison and taken to jail in June.

Marshall was found to be “suffering from a significant and permanent nonterminal condition, disease or syndrome” that has rendered him “physically or cognitively debilitated or incapacitated as to create a reasonable probability” that he doesn’t present a danger to society, the parole board said in a unanimous decision made public Thursday.

The panel told Marshall it considered factors including “the nature of the instant offense, your risk to the community and our finding that there is a reasonable probability that you will live and remain at liberty without violating the law.”

Astor, who suffered from Alzheimer’s disease, died in 2007 at the age of 105. She was one of the last of the American branch of the Astors, a family whose financial and social prestige was once equal to that of the Rockefellers and the Morgans. Marshall, the product of her first marriage, is her only son.

John Jacob

Her third husband was Vincent Astor, who died in 1959. He was heir to the fur and real-estate fortune amassed in the 19th century by John Jacob Astor, who in his time was the wealthiest man in the U.S.

Marshall was accused of taking advantage of his mother partly by trying to obtain millions of dollars she intended for charity. He was motivated by fear that his wife, Charlene, wouldn’t be left with enough money when he died, prosecutors said. Astor, who didn’t like her son’s wife, left her only coats and jewelry, they said.

Marshall’s inheritance was cut by more than half, to $14.5 million from $31 million, in a settlement of his mother’s estate reached in March 2012 that provides $100 million to charities including Central Park, the New York Public Library and the Metropolitan Museum of Art.

Appeals Failed