FORT MYERS, Fla. -

Three people in southwest Florida are accused in the death of a 3-year-old boy.

The Lee County Sheriff's Office says Michael Lee McMullen died Saturday after he was disciplined for behavior problems. The three were arrested Tuesday and charged with aggravated manslaughter of a child.

Authorities say 45-year-old Donella Trainor wrapped the boy in a blanket, tying both ends to keep him from escaping. According sheriff's officials, Trainor put him face down in a crib and he screamed to be released.

A short time later, the child's grandmother entered the room and said the knots were too tight. She left the room, but the child continued to struggle. Eventually the child stopped crying and the adults thought he was sleeping. When Trainor went to wake him, she found him unresponsive.