A college freshman found dead in his Virginia jail cell this summer died of opioid toxicity compounded by asthma, according to the state medical examiner’s office.

Aris Lobo-Perez, who had attended Radford University for three weeks, was found dead at New River Valley Regional Jail on Sept. 12 after his arrest by campus police the night before for public intoxication.

The medical examiner’s office ruled the 18-year-old’s death an accident, but his mother rejected the finding.

“It was neglect,” said Dixiana Perez, adding that police, and then jail guards, “should have taken him to the hospital.”

New River Valley Regional Jail referred questions to the Virginia State Police, which is investigating the death. Corinne Geller, a police spokeswoman, said the investigation is ongoing.

Lobo-Perez arrived at Radford just three weeks before his death. The leafy campus in the southwestern corner of the state was supposed to be a place to start over after a serious car accident in his hometown of Culpeper, Va., a year earlier.

The crash, which left him in a medically induced coma for a month, caused Lobo-Perez to suffer depression and mood swings, his mother said. It also exacerbated his asthma.

Radford was aware of his medical condition, Perez said. The university told The Washington Post in September that it could not comment on a student’s health record.

In the week before his arrest, Lobo-Perez had begun drinking more and using hard drugs, according to friends on campus.

Around 10 p.m. on Sept. 11, the teen posted a video on Snapchat of himself slurring his words and gazing unsteadily into his phone with half-closed eyes.

About half an hour later, a group of students was playing Uno at Radford’s Muse Hall when there was a knock at the door. Students opened it to find a red-eyed Lobo-Perez escorted by a resident assistant. Lobo-Perez, who lived next door, had mistakenly told the RA that this was his room.

“He had white stuff around his mouth,” one student told The Post on the condition of anonymity. “He looked like he was high.”

That student would later message a friend that Lobo-Perez was “foaming at the mouth,” adding, “I just can’t believe the police didn’t take him to the hospital or something.”

Another witness, who described Lobo-Perez the same way to friends, declined to speak to The Post.

The school rejected their accounts, saying it was “unaware of the assertion of any ‘foaming at the mouth,’ as this was not observed by the Radford University Police Department nor was it reported to officers.”

Asked about the medical examiner’s findings Tuesday, the university again said its officers had done nothing wrong.

“The behavior observed by the Radford University Police Department was demonstrative of a person under the influence,” the school said in a statement. “Although he was intoxicated, he conversed with police officers and walked under his own power to the police officer’s cruiser for transport. There was no sign of medical distress. As such, an arrest was made in accordance with Virginia [law], which has a provision for remanding an intoxicated person into custody until they are no longer intoxicated.”

Lobo-Perez rarely went anywhere without his asthma inhaler, which he kept in a fanny pack around his waist, according to his mother. But the university said Tuesday that Lobo-Perez did not have an inhaler when he was arrested.

He was taken to the jail, where a night magistrate required he be held until “no longer intoxicated,” according to a commitment order.

New River Valley’s superintendent, Gregory P. Winston, declined to say whether Lobo-Perez was given a medical exam upon arrival, citing the open investigation. He told The Post in September that Lobo-Perez was put in a cell by himself, as is common for inmates held overnight to sober up.

The teen would have gone before a magistrate again that morning and probably been released, Winston said. Instead, half an hour after declining breakfast at about 7:20 a.m., the teenager was found unresponsive in his cell.

An autopsy did not reveal a cause of death. But a search warrant said state police were investigating Lobo-Perez’s “illegal recreational drug use” the night of his arrest, including what he might have taken and who might have given it to him.

In its report, which was completed last week, the medical examiner ruled that the cause of death was “acute buprenorphine toxicity with acute and chronic asthma contributing,” according to Tracie Cooper, the office’s western district administrator.

Buprenorphine is an opioid used to treat pain and opioid addiction sold under the brand names Suboxone and Subutex. Perez said her son had not been prescribed the drug.

Perez said her family received a call from the medical examiner’s office last week but was unaware the findings would be publicly released. She found out on Monday when she began receiving calls from reporters.

Police should have been aware of her son’s medical condition and taken him to the hospital or called her to pick him up, she said. And guards at the jail should have seen him struggling for breath.

“You can see when someone is having problems breathing,” she said. “Without his inhaler, of course he was going to die.”

Last week, she and her son’s twin sister, Ariela, drove across the state to pick up his belongings. University officials handed Perez a certificate honoring her son’s brief and ill-fated attendance.

“I wanted to throw it in their faces,” Perez said.

Instead, she kept it — one of the few reminders of her son.