SAN DIEGO (AP) — The suspected leader of a drug trafficking ring was among seven students who pleaded not guilty Thursday to charges stemming from an undercover operation at San Diego State University that netted more than 100 arrests.

Kenneth Ciaccio, an honors student at the 34,000-student school, is accused of selling cocaine twice to government agents. He faces up to six years and four months in prison if convicted.

"Ciaccio was identified early as a main source," Deputy District Attorney Shawn Tafreshi said during the court hearing.

Ciaccio and six others pleaded not guilty to selling an array of drugs, including marijuana, Ecstasy, hallucinogenic mushrooms and cocaine. All but one remained in custody in lieu on bonds ranging from $10,000 to $150,000 for Ciaccio.