CONCORD, N.H. — The New Hampshire Supreme Court has rejected an appeal from a New Durham woman accused of starving and torturing a young boy living in her home.

Christina Thomas was convicted three years ago of first-degree assault against her friend’s son while the mother and child lived with her from 2006 to 2010.

Prosecutors accused her of withholding food from the boy, forcing him to stay in a dog cage in her basement, tying him to a bunk bed with a leash and putting him in a crib with a piece of wallboard over it. At other times, he was placed outside in a snowbank or left on the porch in a trash bag, the court said.

In her appeal, Thomas argued that jurors shouldn’t have heard evidence about abuse allegations unrelated to the boy’s feeding, but the court ruled Tuesday that such evidence was relevant in proving her intent.

“The evidence of the other forms of abuse that the defendant perpetrated against (the boy) during the same period that she was depriving him of proper nutrition was relevant to whether she committed the latter conduct knowingly,” the court said in its unanimous ruling. “It tended to show that her failure to provide (him) with proper food was not the result of accident, inadvertence, or a lack of understanding of the nutritional needs of a young child, but rather was part of an obvious and deliberate pattern of abuse.”

The court also rejected Thomas’s argument that jurors should not have heard about other “bad acts,” including her extramarital affair and an incident in which a child she was watching was nearly hit by a car. The court said even if jurors had not heard that information, the evidence against her was overwhelming.

By the time he was removed from the home at age 6, the boy weighed 23 pounds, only six ounces more than when he was 10 months old. The New Hampshire Division for Children, Youth and Families received several reports of neglect and abuse between 2003 and 2010 but all were determined to be unfounded or to not warrant further investigation. He was placed in state custody only after a doctor who treated him during a two-week hospitalization concluded he had been starved and both psychologically and physically tortured.

The boy, who was later adopted, quickly gained weight but continues to have developmental problems.

Thomas is serving a 10- to 30-year sentence.