A mother was sentenced to 20 years in prison Thursday for keeping her 17-year-old adopted son caged in her home.

Brenda Sullivan pleaded guilty in January to three counts of aggravated child abuse. Prosecutors agreed to drop lesser child neglect charges.

The teen weighed 49 pounds when child welfare workers found him in 2005 in what appeared to be a cage. Sullivan told a judge at the time that Ohio authorities told her to keep the boy, who had severe medical and emotional problems, in a crib.

"There's only one conclusion when you look at the medical evidence in this case, and that is that she literally starved him," prosecutor Julie Schlax said.

Two other children, 13-year-old twins the Sullivans adopted as infants, both testified they were kept in similar cages.

Sullivan's husband was also arrested, but died in January 2007 while awaiting trial.

Sullivan's lawyer, Charles Fletcher, said he didn't think prison was the right option because she does not pose a threat to society. He said they would appeal the sentence.