Yet this community fits no neat stereotype of racial tension. It has at times been seen as a model of amicable integration, where students of divergent backgrounds socialize together. And while some students have called the deputy overly rough or racist, others, of all races, defend his record in the school — if not his behavior on the videos.

The videos showed a sheriff’s deputy assigned to Spring Valley High School struggling with a 16-year-old girl who had refused to stand and leave her math class, after the teacher reportedly caught her using her phone. The deputy, Ben Fields, tipped the girl’s chair and desk backward, lifting her out of her seat and slamming her to the floor, and then dragged her to the front of the classroom, where he cuffed her hands behind her back.

Sheriff Leon Lott of Richland County said at a news conference Tuesday that in one video, when the deputy grabbed the girl, she could be seen punching him, but he said his focus was on whether the deputy followed departmental rules. “That’s what the internal affairs investigation is doing, and the results of that will determine his further employment here,” he said.

“Even though she was wrong for disturbing the class, even though she refused to abide by the directions of the teacher, the school administrator and also the verbal commands of our deputy, I’m looking at what our deputy did,” Sheriff Lott said.

He deflected a question about the role of race, saying Deputy Fields has a black girlfriend.

On Monday, the sheriff placed Deputy Fields on unpaid leave, and asked for a federal investigation. The Justice Department’s Civil Rights Division, along with the F.B.I. and the United States attorney for South Carolina, said Tuesday that it would look into the incident.