BOSTON (CBS) — As the U.S. Attorney’s Office investigates alleged incidents of racism at the Boston Latin School, another troubling allegation involving an African-American student has come to light.

Rosalind Wornum told WBZ NewsRadio 1030’s Carl Stevens that her daughter, Destinee, was shocked when an English teacher addressed her using the n-word during a discussion about Huckleberry Finn.

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“It’s embarrassing, it’s insulting, and I mean, the teacher, that’s just straight ignorance,” said Wornum.

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The incident allegedly happened a year and a half ago, when Destinee was a sophomore at Boston Latin School.

Destinee’s mother said she received little response from the headmaster at the time, but said she did get an apology recently.

“The headmaster was apologetic after this whole meeting, and she did say it was unacceptable,” said Wornum.

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Wornum thinks the teacher should be fired.

“What is the penalty?” said Wornum. “There should be something, because you have to draw the line.”

The school department confirmed an investigation into the incident, saying, “The Office of Equity remains steadfast in carrying out its mission of investigating any incident of racism or bias it receives.”

Mayor Marty Walsh said Thursday that the school department is taking the incident seriously.

“It certainly bothers me tremendously,” said Mayor Marty Walsh. “As soon as our Office of Equity found out about it, they reached out to the parent, I believe, to see if they could talk to the child, and to see the circumstances that happened around there.”

Walsh said he certainly doesn’t condone the teacher’s alleged behavior, but did not want to comment on whether or not he thought the teacher should be fired until the investigation is through.

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WBZ NewsRadio 1030’s Carl Stevens reports