A unanimous state appellate panel yesterday upheld a one- to three-year prison sentence for Anthony Marshall, the son of socialite and philanthropist Brooke Astor, who was convicted in 2009 of stealing millions of dollars from his mother’s estate near the end of her life while she was mentally impaired.

The panel in People v. Marshall, 6044/07, also affirmed the conviction of Francis Morrissey, an attorney who worked for Marshall, of forging a document to help Marshall. Morrissey was also sentenced to one to three years.