LOS ANGELES (CBSLA) — CBS2 has obtained autopsy reports for seven of nine USC students who died in a four-month time span during the fall semester of last year — deaths that sent shockwaves through the ritzy campus.

Three of those students died by suicide, one student was hit by two cars while walking on the 110 Freeway and three students died from fentanyl overdoses — a 21-year-old male who majored in cinematic arts, a 21-year-old male who belonged to a fraternity and a 27-year-old male grad student who died at an apartment complex.

A report from the Centers for Disease Control and Prevention showed the number of fentanyl-related deaths were on the rise for people between the ages of 15 and 24, with the steepest rise in fentanyl-related deaths among adults between the ages of 25 and 34.

Fentanyl is a very powerful opioid used for pain management and anesthesia that experts say can kill with an amount equal to a speck of dust.

Dr. Steve Shoptaw, a UCLA professor and clinical psychologist who researchers drug addiction, said “a few grains of fentanyl are going to take you out.”

And what was most concerning was that all the fentanyl-related student deaths were determined by the coroner to be accidental overdoses.

“You’ve got this concentration of deaths among students at USC, so the best way to understand this is, we’re in trouble,” Shoptaw said.

An undercover detective with the Los Angeles Police Department told CBSLA investigative reporter David Goldstein that he investigated the drugs on USC’s campus.

“Me and my unit were tasked to investigate the circumstances of the narcotics flowing to or near the campus,” he said. “We thought we found the big fish on campus.”

Nine days after the last student overdosed in November, police arrested 26-year-old Bill Hsiao. Investigators found drugs, an unregistered rifle and a USC ID card in his apartment just off campus.

Hsiao pleaded no contest to one count of possession for sale of a controlled substance and was sentenced to 49 days in jail. Police have not yet been able to tie him directly to the drugs that led to the deaths of the students, but the investigation is ongoing.

William Bower, special agent in charge with the Drug Enforcement Administration in Los Angeles, said people who bought off the streets could fall prey to fake pills which could contain fentanyl.

“I think the threat of counterfeit prescription drugs is new to us,” he said. “The big issue is it’s not the pill they think it is, and that’s what’s causing a lot of the overdoses.”

Dr. Shoptaw said the fentanyl overdoses at USC were so startling, it prompted changes at UCLA.

In response to this report, USC provided the following statement: