JACKSONVILLE, Fla. -- A woman faces up to 20 years in prison for keeping her 17-year-old adopted son caged in her Jacksonville home.

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

At sentencing early next month, Assistant State Attorney Julie Schlax plans to call witnesses from Ohio, where Sullivan lived before moving her family to Florida.

The teen weighed 49 pounds when child welfare workers found him in 2005 in what appeared to be a cage.

A police report said the boy was starving and suffered psychosocial dwarfism -- a lack of physical and emotional growth caused by abuse. Authorities also say he was forced to wear a diaper.

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.

Sullivan's husband, Wilson, was also arrested, but died in January 2007 while awaiting trial. Brenda Sullivan's bond was recently revoked. A sentencing date has not been scheduled.