The indictments came a week after the three adults were arrested in their home in Wheelersburg, in southern Ohio's Appalachian country.
The adults are charged with three counts each of child endangerment. One of them, a 44-year-old stepfather, also is charged with raping two of the children, girls ages 9 and 11.
The adults' attorneys have declined to comment or ignored requests for comment. The Associated Press is not naming the adults to protect the children's identities.
Since at least May, the three adults are accused of tying and chaining the girls and their 8-year-old brother to their beds so they were "unable to move or get out of the bed" for weeks at a time, according to arrest documents filed in Portsmouth Municipal Court.
The stepfather, who's from the Virgin Islands, is accused of raping each girl multiple times while forcing the other to watch, the documents said.
The children also described being forced to take their clothes off to be beaten, and they had scars to match their stories, Scioto County sheriff's Capt. David Hall said last week.
A school administrator said last week she was proud of the teacher, who called 911 to get help for the children.
Hall said the children, who were removed from the home last week, are in foster care and are attending public school. He said they seem to be doing well and are enjoying normalcy, perhaps for the first time in their lives.
"They told us," he said, "they never had ice cream or a milkshake before."
A 2-year-old girl not believed to have been harmed has joined her siblings in their foster home.
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