On a large campus, college students tend to sell drugs unless they fear getting caught. That’s what Lt. Roy Acree thinks, and that’s why he and the police department at the University of Illinois at Urbana-Champaign planned a mass arrest for last week, following an eight-month undercover investigation.

By last Friday, officers had arrested 25 people, including 21 University of Illinois students, on drug-related charges from misdemeanor cannabis possession to the felony sale of controlled substances, reported The News-Gazette, a Champaign-based newspaper. The campus police dubbed the case “Operation Thunder Strike.”

“By doing this mass type of arrest in a couple of days,” Lieutenant Acree told The Chronicle, the university can “send a message out to the students that if they’re selling drugs, they need to stop.”

That was the goal of a major drug sting last year at San Diego State University. Campus officials there worked with federal agents to arrest 95 students, although a few months later, only half of them still faced charges.

San Diego State’s sting uncovered a network of drug trafficking, but the dealers at Illinois were operating independently, Lieutenant Acree said. He called drug use a perpetual problem on college campuses, and crackdowns somewhat futile.

“It’s pretty much fighting a losing battle to some extent,” Lieutenant Acree said. Still, he said, “we’re going to continue to diligently investigate any type of drug activity.” The police timed last week’s arrest so that the Office for Student Conflict Resolution could work through any disciplinary charges before the end of the semester. —Sara Lipka