Denis Poroy / AP The Phi Kappa Psi house at San Diego State University was one of nine locations served with drug search warrants.

SAN DIEGO — Undercover agents who posed as college students to bust more than 100 suspected drug dealers at San Diego State University never had to crack a book to gain acceptance on campus; all it took was cash.

The federal agents went to one or two parties but never actually went to class or lived in the dorms. Instead, they merely arranged meetings with suspected dealers and asked about buying cocaine, Ecstasy, methamphetamine, marijuana and other drugs, authorities said Wednesday.

"All it took was saying, Hey, I go to State, can you hook me up?" ' said San Diego County prosecutor Damon Mosler. "And then it was off to the races."

The day after the drug sweep landed members of three fraternities in jail and led to the suspension of six frats, investigators revealed how easy it was to penetrate the university's drug culture.

Students who had gotten caught for fighting, drinking, minor drug offenses or other crimes quickly turned informants and used text messages to introduce their drug dealers to undercover agents. Dealers made handoffs in front of dorms, in parking lots or behind frat houses, sometimes in broad daylight in full view of surveillance cameras.

"They never gave any thought that we could be doing an operation there," said Eileen Zeidler, a spokeswoman for the Drug Enforcement Administration office in San Diego.

At least 75 people arrested during the five-month sting were San Diego State students, and 13 of them were from seven fraternities. All together, there were 128 arrests.

The DEA had been on campus at San Diego State before to help investigate a student suspected of cooking methamphetamine for his own use in a campus chemistry lab.

University President Stephen Weber defended the decision to bring federal authorities onto campus.

"Some have asked what we think this publicity has done for SDSU's reputation. I have told them I am proud of the action taken by SDSU to proactively address this serious threat to our students," Weber said in a statement Wednesday. "As a parent I would want my son or daughter to attend a university committed to providing the safest possible environment."

Some students and parents complained that the bust was heavy-handed.

Danielle Patterson, a sophomore sorority member, said she was awake cramming for finals when agents raided an apartment behind her building, pounding on doors and marching young men down the block to the college arena, where they were questioned.

"I never thought something like that would happen here," she said. "To think they think drugs are such a big issue here, it's ridiculous."

Parents joined students at a campus rally Wednesday calling for more drug-abuse treatment instead of tougher enforcement.

"This heavy hand coming down is not going to change drug use on campus," said Gretchen Burns-Bergman, whose son is a month away from graduating. "There's not going to be a shortage of drugs on campus."

During the investigation, agents quickly worked their way to Fraternity Row, where the main target was Theta Chi. They discovered six of its members were operating a sophisticated drug business, with younger "apprentice" members accompanying older members to drug deals in order to learn how the business was run, authorities say.

The ringleader, a 19-year-old, brazenly sent out text messages advertising weekend blowout sales on cocaine, authorities say. Apart from that, however, the fraternity did little to attract attention. In fact, it was known for having a no-alcohol policy at its rundown gray house.

A lawyer for one student arrested last week with about $15,000 worth of cocaine and marijuana did not immediately return a call. The names of the lawyers for some of other defendants could not immediately be learned.