According to Mobile Police, the boy "suffered signs of child abuse."
The victim's 9-year-old sister is accused of beating him with a broom. Court documents cited by WKRG-TV say the victim had injuries that pointed to long-standing abuse.
A probable cause affidavit cited by NBC News says Coale reportedly woke up to sounds of the 4-year-old boy screaming because he was being hit by the broomstick. The affidavit alleges the 9-year-old, "Did willfully torture, willfully abuse, cruelly beat or otherwise willfully maltreat said child by striking the child with a broom stick and/or other dangerous instrument, causing serious physical injury."