As police continued Thursday to probe the death of an Oklahoma teen who died a day after being involved in a fight that broke out in a high school bathroom, authorities announced a preliminary autopsy showed the student's death was not the result of "trauma."

The death of Nex Benedict, 16, has prompted widespread attention and nationwide calls for schools to better protect students who may be bullied because of their gender and sexual identities. Nex, a sophomore at Owasso High School, used they/them and he/him pronouns and identified as gender expansive, an umbrella term that describes people whose gender identity expands beyond traditional gender norms, according to the National Institutes of Health.

Nex had previously been bullied because of their gender identity, friends of Nex told an advocacy group. Authorities are investigating what led up to the fight and whether Nex was targeted because of their gender identity. A police spokesperson, Nick Boatman, told NBC News investigators have reviewed a video that shows Nex before and after the fight and will release it “at some point," the outlet reported.

While the Owasso Police Department said Wednesday that Nex's death was not the result of injuries from a fight, its statement added that the findings were preliminary and investigations by the medical examiner's office and the police department remain underway. The police statement provided no additional details but said an official autopsy would later be released.

"At this time, any further comments on the cause of death are currently pending until toxicology results and other ancillary testing results are received," the police statement said. "The official autopsy report will be available at a later date."

Nex's family says though many questions remain unanswered, the facts of the case so far are troubling. They plan to conduct an independent investigation, relatives confirmed in a statement issued Wednesday. They also urged officials to "hold those responsible to account and to ensure it never happens again."

"While at Owasso High School, Nex was attacked and assaulted in a bathroom by a group of other students," the family said in a statement issued by its attorney. "A day later, the Benedict's beautiful child lost their life."

What happened to Nex Benedict? Search warrant reveals new details

A search warrant filed in the Tulsa County courts Wednesday and obtained by the Oklahoman, part of the USA TODAY network, shed new light on Nex's death and the investigation, including that a detective asked a judge for permission to look for traces of blood and other evidence at Owasso High School.

Penny Hamrick, an Owasso Police detective, wrote in the search warrant that "officers suspect foul play involved and need to initiate an in-depth investigation into the death."

According to the warrant, police were called to an Owasso hospital shortly after 3:30 p.m. on Feb. 7 in response to a report that Nex had been injured in a fight at school. Sue Benedict, Nex's mother, wanted to report the assault and asked police to talk with school administrators about what had happened. She did not ask officers to pursue charges against the other students at that time, Hamrick wrote.

Nex was later discharged from the hospital. But shortly before 3 p.m. the next day, Benedict called 911 to report Nex was experiencing medical issues, including shallow breathing. She told the 911 operator about the altercation at school and said Nex had hit their head on the bathroom floor, Hamrick wrote.

Emergency medical crews performed CPR on Nex and drove them to a Tulsa hospital, where they were pronounced dead around 3:30 p.m.

In the search warrant, Hamrick said police may also look through school records, including photographs, documents and attendance data. Investigators have previously said they plan to spend several days interviewing students and teachers.

FBI, homeland security investigate threat against school staffer

Since Nex's death, a barrage of threats have been made against the Owasso school district and at least one credible threat is being investigated in conjunction with the FBI and the Department of Homeland Security, said Lt. Nick Boatman, a spokesman for Owasso Police.

Boatman said the message that prompted federal agencies to join the investigation included a specific threat of violence against a specific individual. Boatman declined to name the person or disclose any other details about the content of the message. 

Meanwhile, Margaret Coates, the superintendent of Owasso schools, announced in an email that all district schools will have increased security.

A news story that went viral about Nex's death included allegations that teachers failed to summon medical care for the teenager after the altercation, and that Nex was so badly injured in the fight that they could not walk on their own. Police and school officials said the claims were false.

In a statement on Facebook, the Owasso Police Department said each student involved in the fight "walked under their own power to the assistant principal’s office and nurse’s office" after it was broken up. A registered nurse at the school then assessed the health of each student involved in the fight, according to police. Though she determined that "ambulance service was not required," the nurse recommended that Nex "visit a medical facility for further examination," the statement said. Nex was taken to the hospital that afternoon.

Nex Benedict was a 'wonderful child,' sister says

Questions and grief over Nex’s death – at a time when debates over gender and sexuality are becoming increasingly common at school board meetings and legislative hearings nationwide – have spread far beyond the state of Oklahoma. 

On Wednesday, U.S. Education Secretary Miguel Cardona said on X that he was devastated to hear of Nex's death and said more must be done to ensure "transgender and nonbinary students feel safe in schools and in our communities"

“Violence has no place in our school,” Cardona said. “It is our responsibility to protect all students by creating spaces where they feel safe to be their true selves.”

Nex loved to draw, read and play the video games Ark: Survival Evolved and Minecraft, according to their obituary.

“They were a wonderful child, and they were important to us in ways that are really difficult to articulate at this time,” said Malia Pila, the teen’s sister, in a brief conversation with The Oklahoman, part of the USA TODAY network. “They were really great, and we are incredibly sad.”

Nex Benedict suffered bullying, friends tell advocacy group

Nicole McAfee, who leads Freedom Oklahoma, said the organization has been working with some of Nex’s friends and others in Owasso as they process their grief over Nex’s death. The group is focused on making Oklahoma a safer place for people of all genders and sexualities.

McAfee said none of Nex’s friends currently felt comfortable being quoted directly in news stories but that they reported to Freedom Oklahoma that “Nex had been bullied for their gender identity for well over a year."

Jordan Korphage, a spokesman for the school district, did not respond to questions about whether the school had received prior reports of bullying involving Nex. He also would not say what grade Nex was enrolled in or whether the school had any groups aimed at supporting students of various gender and sexual identities.