BOSTON (CBS/AP) — A federal civil rights probe has found that administrators at Boston Latin, the nation’s oldest public school, failed to adequately respond to racist threats made to a black student by a classmate.

U.S. Attorney Carmen Ortiz on Monday announced the civil rights violation and other findings from her office’s months-long probe. The federal investigation was prompted by a request from the NAACP and other civil rights groups.

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Ortiz says the school district is imposing measures to ensure racial discrimination complaints are handled appropriately going forward. The school district, the NAACP and the ACLU didn’t immediately comment.

Former Assistant Headmaster Malcolm Flynn reacted strongly to the news, essentially calling the findings baseless.

“There is no discrimination at Boston Latin School,” Flynn told WBZ-TV. “Students are treated the same way, for the same types of offenses, consistently.”

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In November 2014, a male student allegedly used a racial slur and threatened to “lynch” a black female classmate. A previous school district investigation also concluded the incident was mishandled.

“To claim that there’s a civil rights violation on a case that we did handle in which a student was actually punished seems to me really reaching pretty far,” Flynn said.

He calls the investigation purely political, and it’s why he resigned in June.

“I needed to tell the truth that the mayor of Boston and the superintendent had failed in their duty to support the school or at least tell the truth about the school,” Flynn said.

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