BARABOO, Wis. -- Officials with a Wisconsin school district say free-speech rights would make it difficult to discipline students who appeared in a photograph that showed several high school boys giving what appears to be a Nazi salute.

The State Journal reports that Baraboo Superintendent Lori Mueller said in a letter to parents Wednesday that officials cannot know the "intentions in the hearts" of those involved. She also said the district isn't in a position to punish the students because they are protected by the First Amendment.

The prom photo of about 60 boys was taken outside the Sauk County Courthouse in Baraboo last spring. It prompted international outrage after it surfaced in a now-deleted tweet this month with the caption: "We even got the black kid to throw it up." At least one student is seen making the OK gesture, which some associate with white supremacists.

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The photographer, Peter Gust, defended the students in an interview with a local TV station, saying the gestures are being taken out of context.

"I said, 'OK boys, you're going to say goodbye to your parents. So wave,'" Gust said. "For society to now turn it around and now blame these kids is absolutely wrong."