ST. JOHNSBURY, Vt. — A Vermont woman accused of killing her disabled son after pouring vodka into his feeding tube has been sentenced to up to 12 years in prison.

WCAX-TV reports 41-year-old Melissa Robitille was sentenced to four to 12 years in prison Tuesday. Robitille had previously been found guilty of manslaughter in the 2014 alcohol poisoning death of her 13-year-old son, Isaac.

Prosecutors say Robitille and her boyfriend, Walter Richters, poured vodka in her son’s feeding tube to keep him quiet. The boy later died.

An attorney representing the woman had argued the death was a “tragic mistake.”

Richters was sentenced to three years in prison last year for his role in Isaac’s death.