TAMPA, Fla. (WFLA) — Four people were charged in connection to a University of South Florida student’s fentanyl-related death.

In a news conference Thursday, U.S Attorney Roger Handberg announced charges of conspiracy to distribute fentanyl resulting in death and additional counts of distributing fentanyl (over 40 grams) for Darius Gustafson, 20, Marquise Trant, 35, David Chudhabuddhi, 37, and Miguel Cintron, 36.

The suspects are alleged to be part of a “sophisticated” drug ring, with Cintron working as their leader.

Cintron was also charged with possession with intent to distribute cocaine (over 5 kilograms) and being a felon in possession of a firearm as the result of a search warrant executed April 10.

According to a release from the U.S. Attorney’s Office, law enforcement recovered firearms, several rounds of ammunition, more than seven kilograms of cocaine, one kilogram of black tar heroin, one kilogram of heroin, 1,200 of pressed pills containing fentanyl and over $200k in cash during the search.

All four suspects are being held in jail without bond as they await trial.

Law enforcement began their investigation after the student was found dead in his dorm room in February. It was determined he died of an accidental fentanyl overdose.

Investigators allege the 18-year-old student believed he was buying Percocet pills from Gustafson, but they actually contained fentanyl. There were no other lethal drugs in the student’s system.

Handberg was joined by Col. Chris Rule with the Hillsborough County Sheriff’s Office and Chris Daniel, Chief of Public Safety at the University of South Florida Police Department, who discussed their agencies’ roles in the investigation.