After a student took LSD, ran through a fifth-floor window of a residence hall at George Mason University and plunged to his death in September, campus police opened a death probe that quickly expanded, according to search warrants.

A GMU police detective discovered George Mason exams on the student’s laptop, according to the newly unsealed court documents, and investigated the possibility that a school fraternity maintains and distributes a “bank” of such exams. No charges were ever filed, and the criminal investigation was closed.

But university spokesman Michael Sandler wrote in a statement Tuesday that the school has launched an administrative investigation into the fraternity, which has been temporarily suspended, and GMU students involved. Court documents identify the fraternity as Sigma Alpha Epsilon.

“Police discovered a test bank, which included images of university exams that people could access,” Sandler wrote. “The issue of the test bank was referred to the Office of Student Conduct to look into the misuse of university documents.”

Sandler said federal law prevents the school from identifying any students involved or discussing any potential discipline.

The student who died, Tristan Tanner Medina, 19, of Fredericksburg, Va., jumped from a window of the Potomac Heights residence hall on campus around 4:40 p.m. on Sept. 30, according to the search warrants in Fairfax County.

Police interviews revealed Medina had consumed LSD earlier in the day, according to the search warrant. Detectives also found that he had a history of depression and suicidal thoughts.

Jill Medina, the student’s mother, said she does not believe the sophomore, who was majoring in criminal justice, took his own life. She said he lived with five other members of his fraternity.

“We don’t think it was a suicide. We think it was the effects of the drugs,” Medina said. “He was an athlete. He was a go-getter. He was friendly to everyone. He had the best sense of humor.”

Medina said she was not aware that police had allegedly discovered exams on her son’s computer. She said she has been frustrated by the lack of information the university has given her about the circumstances surrounding the death. She has hired an attorney to help.

Her son, one of three brothers, was a running back at Massaponax High School in Fredericksburg.

The investigation grew after officers conducted a search of Tristan Medina’s room at the university, finding two laptops, according to the search warrants. The detectives discovered what appeared to be university exams on a laptop.

A test distributor confirmed that one of the documents was the property of George Mason and should not have been available outside the exam room, according to the search warrants.

The warrants, filed in Fairfax County Circuit Court, do not detail what subject the exam covered, but detectives wrote that the test was used for academic credit and undergoes little modification from semester to semester. The exam is administered on paper, so someone could have illicitly scanned or taken a photograph of it.

Police said in court papers that they interviewed Medina’s roommate, who said he had exchanged messages with the president of Sigma Alpha Epsilon on the date of the incident.

Detectives wrote in the search warrant that Medina’s roommate consented to a search of his phone, which the detective said revealed the illegal transfer of exam materials throughout the fraternity.

“Yo...how can I get one of the tests from our test bank?” a message from Medina’s roommate to the fraternity president read. The president told Medina’s roommate to contact the vice president of the fraternity for the materials and said he had sent them to someone else earlier.

The detective wrote that she “has cause to believe that [the fraternity president] illegally has access to, maintains, and distributes a ‘bank’ of materials intended to be submitted for academic credit at George Mason University.”

The search warrant does not say how many exams are allegedly in the bank or how many people potentially received them.

The Washington Post is not naming the fraternity president or roommate because neither has been charged with a crime. When reached Tuesday, the fraternity president said he would have to speak with his attorney before commenting. He never called back.

The fraternity president’s mother said her son did nothing wrong and the test bank was simply a collection of old tests.

The detective has filed search warrants for a computer, the homes of two fraternity members and a car. According to the court papers, the searches have turned up test papers, study guides, ­Scantrons and marijuana.

The searches were conducted under a Virginia law that makes it illegal to prepare or sell academic papers with the knowledge that they will be submitted by another person to a college or university for credit.

GMU has nearly 36,000 students, and its main campus is in Fairfax.

Researchers have found that cheating of one sort or another — whether Internet-facilitated plagiarism or homework help that crosses the line — is a widespread phenomenon on campuses. But exactly how often “test banks” are used on college campuses for systematic cheating is unknown, because those who utilize the technique do not willingly report it. One expert said the practice is thought to be relatively common.

“It is very typical, at least in the lore, for social organizations to maintain these test banks,” said David Rettinger, president of the International Center for Academic Integrity and associate professor of psychological science at the University of Mary Washington. “Obviously it’s against the rules and undermines the learning that faculty hope will occur.”

Rettinger said professors know that the moment a copy of a test is released to anyone, it could be filed away for illicit academic purposes. “Once it leaves the printer, most of us accept that it’s impossible to maintain security on things like that,” he said. The solution, he said, is to revise tests as often as possible.