The Department of Education is opening an investigation into whether the Oklahoma school district where the late 16-year-old transgender student Nex Benedict attended high school failed to appropriately respond to sex-based harassment, according to a letter obtained by NBC News on Friday.

The letter was addressed to the Human Rights Campaign, the country’s largest LGBTQ rights group, which had filed a complaint with the department following Benedict’s Feb. 8 death.

Benedict died a day after engaging in a fight with three other students in a school bathroom at Owasso High School, in a case that has drawn intense media attention and condemnation from LGBTQ advocates around the world. 

In its complaint, the HRC called on the Department of Education to investigate the district for failing “to address the discrimination and harassment to which Nex was subjected” and to determine whether the district violated Title IX, a landmark civil rights law that protects people from gender-based discrimination in education programs funded by the federal government.

“This letter is to notify you that the U.S. Department of Education, Office for Civil Rights (OCR), is opening for investigation the above-referenced complaint that you filed against the Owasso Public Schools (the District),” Karen E. Mines, the Education Department’s chief attorney, wrote in a letter to the HRC. “Your complaint alleges that the District discriminated against students by failing to respond appropriately to sex-based harassment, of which it had notice, at Owasso High School during the 2023-2024 school year.”

Mines added that the department will be investigating whether the district failed to appropriately respond to alleged harassment of students “in a manner consistent with the requirements of Title IX.”

Neither the Education Department nor Owasso Public Schools immediately returned requests for comment.

It is still unclear what caused Benedict’s death and whether or not Benedict’s fight with three other high schoolers played a role in his death.

In body camera footage from a police officer’s interview with Benedict on Feb. 7, the day of the fight, Benedict can be heard telling the officer that three students attacked him in the bathroom. The teen also said he threw water on the students prior to the fight, because they had bullied him and his friends for the way they dressed.

“Nex’s family, community, and the broader 2SLGBTQI+ (two spirit, lesbian, gay, bisexual, transgender, queer, and intersex+) community in Oklahoma are still awaiting answers following their tragic loss,” Kelley Robinson, the HRC’s president, said in a statement Friday evening. “We appreciate the Department of Education responding to our complaint and opening an investigation–we need them to act urgently so there can be justice for Nex, and so that all students at Owasso High School and every school in Oklahoma can be safe from bullying, harassment, and discrimination.”