When police said a girl arrived at Hayes Elementary School in Davenport Friday looking like she was "in a car wreck," school officials notified authorities and began an investigation.

Police discovered that 35-year-old Susanna Michelle Miller of Davenport was beating her boyfriend's three small children while they were in her care, according to court records.

Miller was arrested Friday night and is awaiting her first appearance in Scott County District Court, Davenport. She's charged with two felony counts and one misdemeanor count of child endangerment with injury.

The victims are ages 3, 6, and 9 and are the biological children of Miller's boyfriend, records state.

The girl who attends Hayes went to school with bruises all over her body, according to school staff. Authorities have discovered that her two siblings also had noticeable and extreme bruising, records state.

Witnesses told police that they have seen Miller physically assaulting the three children over the past several months, according to her arrest affidavit.

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On Friday, a witness who visited Miller at her house saw one of the children walk out of a room with blood running from the back of his head, the affidavit states.

She was the primary caregiver of the three children at the time of the assaults, the affidavit states.

Her record includes two misdemeanor assault convictions. She pleaded guilty to assault causing bodily injury in 1997 and to simple assault in 2009. Both times, she was sentenced to one year of probation.